## Compiler magic

22 février 2017

How do you efficiently divide by 19? All you need is some compiler magic!  It’s all explained here!

## 1001001 SOS

10 février 2017

I’ve been dealing a lot with bit operations lately.  And doing lots of benchmarking, like here. As I was looking for a bit count method in Pharo (it used to be there but it no longer exists in Pharo 5.0), I got curious about the many different versions of bit counting algorithms I could find on the internet.

What’s so special about bit operations you ask?  Not much.  Except when you have to do it really fast on 64bit integers!  Like in a chess program!  Millions of times per position. So instead of copying the #bitCount method that was in Squeak, I decided I’d have a look at what is available on the net…

So I decided to share what I found.  This could potentially be useful for people who have to deal with bit counting a lot. Especially if you deal with 14 bits or less!

Here’s a typical run of the different bit counting algorithms I have tested on Squeak 5.1 64bit.

```Number of [myBitCount1 (128 bits)] per second: 0.061M
Number of [myBitCount1 (14 bits)] per second: 1.417M
Number of [myBitCount1 (16 bits)] per second: 1.271M
Number of [myBitCount1 (30 bits)] per second: 0.698M
Number of [myBitCount1 (32 bits)] per second: 0.651M
Number of [myBitCount1 (60 bits)] per second: 0.362M
Number of [myBitCount1 (64 bits)] per second: 0.131M
Number of [myBitCount1 (8 bits)] per second: 2.255M
Number of [myBitCount2 (128 bits)] per second: 0.286M
Number of [myBitCount2 (14 bits)] per second: 3.623M
Number of [myBitCount2 (16 bits)] per second: 3.630M
Number of [myBitCount2 (30 bits)] per second: 2.320M
Number of [myBitCount2 (32 bits)] per second: 2.336M
Number of [myBitCount2 (60 bits)] per second: 1.415M
Number of [myBitCount2 (64 bits)] per second: 1.208M
Number of [myBitCount2 (8 bits)] per second: 4.950M
Number of [myBitCount3 (128 bits)] per second: 0.498M
Number of [myBitCount3 (14 bits)] per second: 4.556M
Number of [myBitCount3 (16 bits)] per second: 4.673M
Number of [myBitCount3 (30 bits)] per second: 3.401M
Number of [myBitCount3 (32 bits)] per second: 3.401M
Number of [myBitCount3 (60 bits)] per second: 2.130M
Number of [myBitCount3 (64 bits)] per second: 1.674M
Number of [myBitCount3 (8 bits)] per second: 4.938M
Number of [myBitCount4 (128 bits)] per second: 0.041M
Number of [myBitCount4 (14 bits)] per second: 5.333M
Number of [myBitCount4 (16 bits)] per second: 4.819M
Number of [myBitCount4 (30 bits)] per second: 2.841M
Number of [myBitCount4 (32 bits)] per second: 2.674M
Number of [myBitCount4 (60 bits)] per second: 1.499M
Number of [myBitCount4 (64 bits)] per second: 0.270M
Number of [myBitCount4 (8 bits)] per second: 7.435M
Number of [myBitCount5 (128 bits)] per second: 0.377M
Number of [myBitCount5 (14 bits)] per second: 3.937M
Number of [myBitCount5 (16 bits)] per second: 3.035M
Number of [myBitCount5 (30 bits)] per second: 2.137M
Number of [myBitCount5 (32 bits)] per second: 2.035M
Number of [myBitCount5 (60 bits)] per second: 1.386M
Number of [myBitCount5 (64 bits)] per second: 1.188M
Number of [myBitCount5 (8 bits)] per second: 4.167M
Number of [myBitCount6 (128 bits)] per second: 0.381M
Number of [myBitCount6 (14 bits)] per second: 5.195M
Number of [myBitCount6 (16 bits)] per second: 3.552M
Number of [myBitCount6 (30 bits)] per second: 2.488M
Number of [myBitCount6 (32 bits)] per second: 2.364M
Number of [myBitCount6 (60 bits)] per second: 1.555M
Number of [myBitCount6 (64 bits)] per second: 1.284M
Number of [myBitCount6 (8 bits)] per second: 5.571M
Number of [myPopCount14bit (14 bits)] per second: 18.349M
Number of [myPopCount14bit (8 bits)] per second: 18.519M
Number of [myPopCount24bit (14 bits)] per second: 7.407M
Number of [myPopCount24bit (16 bits)] per second: 7.463M
Number of [myPopCount24bit (8 bits)] per second: 7.018M
Number of [myPopCount32bit (14 bits)] per second: 4.963M
Number of [myPopCount32bit (16 bits)] per second: 5.013M
Number of [myPopCount32bit (30 bits)] per second: 4.608M
Number of [myPopCount32bit (32 bits)] per second: 4.619M
Number of [myPopCount32bit (8 bits)] per second: 4.608M
Number of [myPopCount64a (14 bits)] per second: 2.778M
Number of [myPopCount64a (16 bits)] per second: 2.793M
Number of [myPopCount64a (30 bits)] per second: 2.751M
Number of [myPopCount64a (32 bits)] per second: 2.703M
Number of [myPopCount64a (60 bits)] per second: 2.809M
Number of [myPopCount64a (64 bits)] per second: 1.385M
Number of [myPopCount64a (8 bits)] per second: 2.755M
Number of [myPopCount64b (14 bits)] per second: 3.063M
Number of [myPopCount64b (16 bits)] per second: 3.096M
Number of [myPopCount64b (30 bits)] per second: 3.106M
Number of [myPopCount64b (32 bits)] per second: 3.053M
Number of [myPopCount64b (60 bits)] per second: 3.008M
Number of [myPopCount64b (64 bits)] per second: 1.444M
Number of [myPopCount64b (8 bits)] per second: 3.091M
Number of [myPopCount64c (14 bits)] per second: 1.625M
Number of [myPopCount64c (16 bits)] per second: 1.600M
Number of [myPopCount64c (30 bits)] per second: 1.542M
Number of [myPopCount64c (32 bits)] per second: 1.529M
Number of [myPopCount64c (60 bits)] per second: 1.566M
Number of [myPopCount64c (64 bits)] per second: 1.082M
Number of [myPopCount64c (8 bits)] per second: 3.945M
```

Now, since method #myBitCount2 is similar to the #bitCount method in Squeak, that means there is still place for improvement as far as a faster #bitCount is needed.  Now the question is : do we optimize it for the usual usage (SmallInteger), for 64bit integer or we use an algorithm that performs relatively well in most cases?  Obviously, since I will always be working with 64bit positive integers, I have the luxury to pick a method that precisely works best in my specific case!

All test code I have used can be found here.

Note: Rush fans have probably noticed the reference in the title…

## Bits and Pieces

10 février 2017

Often times, we take stuff for granted.  But while preparing to embark on a crazy project (description in French here and Google translation in English here), I wanted to benchmark the bit manipulation operations in both Squeak and Pharo, for the 32bit and 64bit images (I am on Windows so the 64bit VM is not available for testing yet but it’ll come!).  So essentially, it was just a test to compare the VM-Image-Environment combo!

To make a long story short, I was interested in testing the speed of 64bit operations on positive integers for my chess program. I quickly found some cases where LargePositiveInteger operations were more than 7-12 times slower than the SmallInteger equivalences and I became curious since it seemed like a lot.  After more testing and discussions (both offline and online), someone suggested that some LargePositiveInteger operations could possibly be slow because they were not inlined in the JIT.  It was then recommended that I override those methods in LargePositiveInteger (with primitives 34 to 37), thus shortcutting the default and slow methods in Integer (corresponding named primitives, primDigitBitAnd, primDigitBitOr, primDigitBitXorprimDigitBitShiftMagnitude in LargeIntegers module).  I immediately got a 2-3x speedup for LargePositiveInteger but…

Things have obviously changed in the Squeak 64bit image since some original methods (in class Integer) like #bitAnd: and #bitOr: are way faster than the overrides (in class LargePositiveInteger )!  Is it special code in the VM that checks for 32bit vs 64bit (more precisely, 30bit vs 60bit integers)?  Is it in the LargeIntegers module?

Here are 2 typical runs for Squeak 5.1 32bit (by the way, Pharo 32bit image performs similarly) and Squeak 5.1 64bit images  :

Squeak 5.1 32bit

```Number of #allMask: per second: 7.637M
Number of #anyMask: per second: 8.333M
Number of #bitAnd: per second: 17.877M
Number of #bitAnd2: per second: 42.105M
Method #bitAnd2: seems to work properly! Overide of #bitAnd: in LargeInteger works!
Number of #bitAt: per second: 12.075M
Number of #bitAt:put: per second: 6.287M
Number of #bitClear: per second: 6.737M
Number of #bitInvert per second: 5.536M
Number of #bitOr: per second: 15.764M
Number of #bitOr2: per second: 34.409M
Method #bitOr2: seems to work properly! Overide of #bitOr: in LargeInteger works!
Method #bitShift2: (left & right shifts) seems to work properly! Overide of #bitShift: in LargeInteger works!
Number of #bitXor: per second: 15.385M
Number of #bitXor2: per second: 34.043M
Method #bitXor2: seems to work properly! Overide of #bitXor: in LargeInteger works!
Number of #highBit per second: 12.451M
Number of #<< per second: 6.517M
Number of #bitLeftShift2: per second: 8.399M
Number of #lowBit per second: 10.702M
Number of #noMask: per second: 7.064M
Number of #>> per second: 7.323M
Number of #bitRightShift2: per second: 29.358M
```

Squeak 5.1 64bit

```Number of #allMask: per second: 36.782M
Number of #anyMask: per second: 41.026M
Number of #bitAnd: per second: 139.130M
Number of #bitAnd2: per second: 57.143M
Method #bitAnd2: seems to work properly! Overide of #bitAnd: in LargeInteger works!
Number of #bitAt: per second: 23.358M
Number of #bitAt:put: per second: 8.649M
Number of #bitClear: per second: 38.554M
Number of #bitInvert per second: 29.630M
Number of #bitOr: per second: 139.130M
Number of #bitOr2: per second: 58.182M
Method #bitOr2: seems to work properly! Overide of #bitOr: in LargeInteger works!
Method #bitShift2: (left & right shifts) seems to work properly! Overide of #bitShift: in LargeInteger works!
Number of #bitXor: per second: 55.172M
Number of #bitXor2: per second: 74.419M
Method #bitXor2: seems to work properly! Overide of #bitXor: in LargeInteger works!
Number of #highBit per second: 7.921M
Number of #<< per second: 10.127M
Number of #bitLeftShift2: per second: 12.800M
Number of #lowBit per second: 6.823M
Number of #noMask: per second: 39.024M
Number of #>> per second: 23.188M
Number of #bitRightShift2: per second: 56.140M
```

So now, I’m left with 2 questions :

1. Why exactly does the override work (in 32bit images)?
2. What changed so that things are different in Squeak 5.1 64bit image (overrides partially work)?

If you’re curious/interested, the code I have used to test is here.

Leave me a comment (or email) if you have an explanation!

To be continued…

## Comment presser un citron (troisième partie)

27 mai 2013

1. Un problème n’arrive jamais seul

Dans la deuxième partie de cet article (le premier article étant ici), nous nous sommes laissés sur un exemple extrême (i.e. une grille avec des lignes et des colonnes vides) afin de vérifier la validité et l’efficacité de la solution présentée dans un des pires scénarios envisageable :

Avant même de débuter, rappelez-vous qu’il est primordial d’exécuter la commande suivante dans votre session pour éviter d’avoir à attendre une éternité, que ce soit pour la requête SQL ou pour un EXPLAIN!

```set @@optimizer_search_depth = 3;
```

Qu’arriverait-il si nous avions à solutionner un sudoku contenant à la fois des lignes et des colonnes vides, comme dans l’exemple ci-haut avec la requête suivante:

```SELECT *
FROM sudoku_combined_view
WHERE
(r2c2 = 3) AND (r2c3 = 4) AND (r2c4 = 8) AND (r2c5 = 2) AND
(r2c6 = 5) AND (r2c7 = 6) AND (r2c8 = 9) AND (r3c2 = 5) AND
(r3c3 = 9) AND (r3c4 = 3) AND (r3c5 = 6) AND (r3c6 = 4) AND
(r3c7 = 1) AND (r3c8 = 8) AND (r4c2 = 9) AND (r4c3 = 7) AND
(r4c4 = 1) AND (r4c5 = 8) AND (r4c6 = 2) AND (r4c7 = 5) AND
(r4c8 = 6) AND (r6c2 = 8) AND (r6c3 = 1) AND (r6c4 = 4) AND
(r6c5 = 7) AND (r6c6 = 6) AND (r6c7 = 2) AND (r6c8 = 3) AND
(r7c2 = 2) AND (r7c3 = 5) AND (r7c4 = 6) AND (r7c5 = 4) AND
(r7c6 = 1) AND (r7c7 = 9) AND (r7c8 = 7) AND (r8c2 = 7) AND
(r8c3 = 6) AND (r8c4 = 5) AND (r8c5 = 3) AND (r8c6 = 8) AND
(r8c7 = 4) AND (r8c8 = 2);
```

Examinons le résultat du EXPLAIN pour la grille en question:

```+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+---------+-------------------------------+------+----------------------------------------------------------+
| id | select_type | table | type        | possible_keys                                                                                                                                      | key         | key_len | ref                           | rows | Extra                                                    |
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+---------+-------------------------------+------+----------------------------------------------------------+
|  1 | SIMPLE      | col3  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i38,i48 | 2,2,2   | NULL                          |   64 | Using intersect(i23,i38,i48); Using where                |
|  1 | SIMPLE      | r2    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i58     | 2,2     | NULL                          |   68 | Using intersect(i23,i58); Using where; Using join buffer |
|  1 | SIMPLE      | r3    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i78,i56     | 2,2     | NULL                          |   68 | Using intersect(i78,i56); Using where; Using join buffer |
|  1 | SIMPLE      | r4    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i38,i46     | 2,2     | NULL                          |   68 | Using intersect(i38,i46); Using where; Using join buffer |
|  1 | SIMPLE      | r6    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i67     | 2,2     | NULL                          |   68 | Using intersect(i23,i67); Using where; Using join buffer |
|  1 | SIMPLE      | r7    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i38,i56     | 2,2     | NULL                          |   68 | Using intersect(i38,i56); Using where; Using join buffer |
|  1 | SIMPLE      | r8    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i68     | 2,2     | NULL                          |   68 | Using intersect(i23,i68); Using where; Using join buffer |
|  1 | SIMPLE      | col2  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i68     | 2,2     | NULL                          |   68 | Using intersect(i23,i68); Using where; Using join buffer |
|  1 | SIMPLE      | col4  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i78,i46     | 2,2     | NULL                          |   68 | Using intersect(i78,i46); Using where; Using join buffer |
|  1 | SIMPLE      | col5  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i68     | 2,2     | NULL                          |   68 | Using intersect(i23,i68); Using where; Using join buffer |
|  1 | SIMPLE      | col6  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i67     | 2,2     | NULL                          |   68 | Using intersect(i23,i67); Using where; Using join buffer |
|  1 | SIMPLE      | col7  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23,i68     | 2,2     | NULL                          |   68 | Using intersect(i23,i68); Using where; Using join buffer |
|  1 | SIMPLE      | col8  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i37,i24     | 2,2     | NULL                          |   68 | Using intersect(i37,i24); Using where; Using join buffer |
|  1 | SIMPLE      | col1  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i23         | 2       | sudoku.r2.c1,sudoku.r3.c1     | 5040 | Using where                                              |
|  1 | SIMPLE      | r1    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12         | 2       | sudoku.col1.c1,sudoku.col2.c1 | 5040 | Using where                                              |
|  1 | SIMPLE      | r5    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12         | 2       | sudoku.col1.c5,sudoku.col2.c5 | 5040 | Using where                                              |
|  1 | SIMPLE      | r9    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12         | 2       | sudoku.col1.c9,sudoku.col2.c9 | 5040 | Using where                                              |
|  1 | SIMPLE      | col9  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12         | 2       | sudoku.r1.c9,sudoku.r2.c9     | 5040 | Using where                                              |
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+---------+-------------------------------+------+----------------------------------------------------------+
18 rows in set (0.20 sec)```

À première vue, tout semble correct! Aucun table scan et les indexes sont utilisés pour chaque colonne et chaque rangée non vide!

Et en combien de temps MySQL peut-il « solutionner » cette grille ?

Fantastique!  1.5 seconde!  Tout est réglé!  Malheureusement, non…

2. Le pire scénario possible

Il existe une catégorie de sudokus que nombre de mathématiciens et d’informaticiens étudient depuis des années : ces grilles minimales n’ont seulement que 17 révélés, le minimum théorique (une conjecture encore non prouvée de façon mathématique par Gary McGuire, Bastian Tugemann et Gilles Civario, un autre intéressant article ici) pouvant mener à une solution unique.  Plusieurs de ces grilles spéciales (17 révélés) sont depuis des années compilées par Gordon Royle, professeur à l’université d’Australie Occidentale.

Comme celle-ci :

Vous remarquerez que cette grille ne contient aucune ligne ni aucune colonne vide! Essayons donc de voir en combien de temps MySQL pourra résoudre celle-ci :

```mysql> SELECT *
-> FROM sudoku_combined_view
-> WHERE
-> (r1c8 = 1) AND
-> (r2c1 = 4) AND
-> (r3c2 = 2) AND
-> (r4c5 = 5) AND
-> (r4c7 = 4) AND
-> (r4c9 = 7) AND
-> (r5c3 = 8) AND
-> (r5c7 = 3) AND
-> (r6c3 = 1) AND
-> (r6c5 = 9) AND
-> (r7c1 = 3) AND
-> (r7c4 = 4) AND
-> (r7c7 = 2) AND
-> (r8c2 = 5) AND
-> (r8c4 = 1) AND
-> (r9c4 = 8) AND
-> (r9c6 = 6);
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
| r1c1 | r1c2 | r1c3 | r1c4 | r1c5 | r1c6 | r1c7 | r1c8 | r1c9 | r2c1 | r2c2 | r2c3 | r2c4 | r2c5 | r2c6 | r2c7 | r2c8 | r2c9 | r3c1 | r3c2 | r3c3 | r3c4 | r3c5 | r3c6 | r3c7 | r3c8 | r3c9 | r4c1 | r4c2 | r4c3 | r4c4 | r4c5 | r4c6 | r4c7 | r4c8 | r4c9 | r5c1 | r5c2 | r5c3 | r5c4 | r5c5 | r5c6 | r5c7 | r5c8 | r5c9 | r6c1 | r6c2 | r6c3 | r6c4 | r6c5 | r6c6 | r6c7 | r6c8 | r6c9 | r7c1 | r7c2 | r7c3 | r7c4 | r7c5 | r7c6 | r7c7 | r7c8 | r7c9 | r8c1 | r8c2 | r8c3 | r8c4 | r8c5 | r8c6 | r8c7 | r8c8 | r8c9 | r9c1 | r9c2 | r9c3 | r9c4 | r9c5 | r9c6 | r9c7 | r9c8 | r9c9 |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
|   6  |   9  |   3  |   7  |   8  |   4  |   5  |   1  |   2  |   4  |   8  |   7  |   5  |   1  |   2  |   9  |   3  |   6  |   1  |   2  |   5  |   9  |   6  |   3  |   8  |   7  |   4  |   9  |   3  |   2  |   6  |   5  |   1  |   4  |   8  |   7  |   5  |   6  |   8  |   2  |   4  |   7  |   3  |   9  |   1  |   7  |   4  |   1  |   3  |   9  |   8  |   6  |   2  |   5  |   3  |   1  |   9  |   4  |   7  |   5  |   2  |   6  |   8  |   8  |   5  |   6  |   1  |   2  |   9  |   7  |   4  |   3  |   2  |   7  |   4  |   8  |   3  |   6  |   1  |   5  |   9  |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
1 row in set (2 min 20.83 sec)
```

Ouch!  Je ne suis pas arrivé à descendre sour la barre des 40 secondes malgré mes tentatives répétées et ce, sur différents serveurs avec différentes configurations (et même différentes autres grilles de 17 révélés). Les résultats pour solutionner cette grille vont de près de 40 secondes à plus de 33 minutes. Le résultat du EXPLAIN parle par lui-même :

```+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+---------+---------+-------------------------------+------+----------------------------------------------------------+
| id | select_type | table | type        | possible_keys                                                                                                                                      | key     | key_len | ref                           | rows | Extra                                                    |
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+---------+---------+-------------------------------+------+----------------------------------------------------------+
|  1 | SIMPLE      | r4    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i57,i59 | 2,2     | NULL                          |  624 | Using intersect(i57,i59); Using where                    |
|  1 | SIMPLE      | r7    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i14,i47 | 2,2     | NULL                          |  624 | Using intersect(i14,i47); Using where; Using join buffer |
|  1 | SIMPLE      | col4  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i78,i89 | 2,2     | NULL                          |  624 | Using intersect(i78,i89); Using where; Using join buffer |
|  1 | SIMPLE      | col7  | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i45,i47 | 2,2     | NULL                          |  624 | Using intersect(i45,i47); Using where; Using join buffer |
|  1 | SIMPLE      | r8    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i24     | 2       | const,const                   | 5000 | Using where                                              |
|  1 | SIMPLE      | r9    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i46     | 2       | const,const                   | 5001 | Using where                                              |
|  1 | SIMPLE      | col1  | range       | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i27     | 2       | NULL                          | 5000 | Using where; Using join buffer                           |
|  1 | SIMPLE      | r5    | range       | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i37     | 2       | NULL                          | 5001 | Using where; Using join buffer                           |
|  1 | SIMPLE      | r6    | range       | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i35     | 2       | NULL                          | 5001 | Using where; Using join buffer                           |
|  1 | SIMPLE      | col3  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i45     | 2       | sudoku.r4.c3,const            | 5040 | Using where                                              |
|  1 | SIMPLE      | col2  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i34     | 2       | const,sudoku.r4.c2            | 5040 | Using where                                              |
|  1 | SIMPLE      | r2    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12     | 2       | const,sudoku.col2.c2          | 5040 | Using where                                              |
|  1 | SIMPLE      | col5  | range       | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i46     | 2       | NULL                          | 5001 | Using where; Using join buffer                           |
|  1 | SIMPLE      | r3    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12     | 2       | sudoku.col1.c3,const          | 5040 | Using where                                              |
|  1 | SIMPLE      | col8  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12     | 2       | const,sudoku.r2.c8            | 5040 | Using where                                              |
|  1 | SIMPLE      | r1    | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12     | 2       | sudoku.col1.c1,sudoku.col2.c1 | 5040 | Using where                                              |
|  1 | SIMPLE      | col9  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12     | 2       | sudoku.r1.c9,sudoku.r2.c9     | 5040 | Using where                                              |
|  1 | SIMPLE      | col6  | ref         | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12     | 2       | sudoku.r1.c6,sudoku.r2.c6     | 5040 | Using where                                              |
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+---------+---------+-------------------------------+------+----------------------------------------------------------+
18 rows in set (2.59 sec)```

Observez la colonne rows dans le résultat du EXPLAIN pour comprendre le nombre astronomique de jointures possibles que MySQL aura à effectuer et à tester…  Dans la très grande majorité des cas, ce chiffre est supérieur à 5000!

Il devient maintenant évident que notre solution ne tient plus la route…

3. Ne pas céder au découragement!

Il existe bon nombre d’autres possibilités d’optimisations que nous n’avons toujours pas envisagées.  Par exemple, dans certains cas il pourrait être avantageux de chercher par boîtes (carré de 3×3 dans le sudoku).  Certaines grilles de 17 révélés pourraient grandement en bénéficier mais il nous faudrait alors joindre 27 tables!  Ce qui est gagné d’un côté est perdu de l’autre.

Nous pourrions également créer des partitions mais dans ce cas, quelles seraient les chances qu’une colonne ou une rangée contienne la donnée permettant de discriminer et de choisir la partition requise?

Nous pourrions augmenter la taille de l’index pour passer de 2 colones à 3 mais l’impact de cette mesure serait inutile pour les grilles de 17 révélés.

Qu’arriverait-il si nous passions du format de table MyISAM à InnoDb ?  Absolument rien, le problème demeure entier : MySQL n’est pas assez rapide pour lire les données (ou les indexes) sur disque puis les joindre efficacement dans un cas aussi extrême.

L’idée à la base de cette série d’article était d’arriver à solutionner un sudoku valide en n’utilisant que du SQL.  Un sudoku valide, par définition, a une seule solution.  Nous aurions pu ajouter LIMIT 1 à chacune de nos vues mais hélas, ce faisant, nos vues seraient contraintes d’utiliser l’algorithme TEMPTABLE au lieu de MERGE, ce qui serait catastrophique!

Évidemment, quelques autres astuces existent, comme augmenter la taille des variables key_buffer_size et join_buffer_size, diminuer la valeur du optimizer_search_depth, etc.  Évidemment dans le cas des 2 premières variables, je ne peux rien vous suggérer comme ces paramètres dépendent de la mémoire RAM disponible sur votre machine, le système d’exploitation utilisé, etc.  Quant à la valeur de la variable optimizer_search_depth, diminuer celle-ci n’aura pas d’impact significatif comme le problème réside dans la lenteur des accès au disque dur et au nombre effarant de jointures et de rangées à examnier (et à retrouver puis lire).

4. Éplucher toutes les options

Il existe un type de table, MEMORY, en MySQL qui nous permettrait d’éviter d’avoir à lire les données (ou les indexes) sur disque, ce qui pourrait avoir un impact majeur dans notre cas.  Nous allons donc créer cette table en mémoire et la remplir tout en créant les indexes nécessaires (exactement les mêmes vues et indexes que la table de format MyISAM).

Mais avant de procéder, prenez bien soin de vous assurez que la variable max_heap_table_size soit supérieure à 216Mb ( 226492416) sinon vous vous heurterez à une tonne d’erreurs 1114 (table full).  Si ce n’est pas le cas, vous pouvez fixer la valeur de cette variable à 216Mb comme suit :

```set @@max_heap_table_size =  226492416;
```

Une fois cette précaution prise, construisez la table et les indexes nécessaires comme suit:

```USE sudoku;

DROP TABLE IF EXISTS positions_memory;
CREATE TABLE positions_memory (
c1 TINYINT UNSIGNED NOT NULL,
c2 TINYINT UNSIGNED NOT NULL,
c3 TINYINT UNSIGNED NOT NULL,
c4 TINYINT UNSIGNED NOT NULL,
c5 TINYINT UNSIGNED NOT NULL,
c6 TINYINT UNSIGNED NOT NULL,
c7 TINYINT UNSIGNED NOT NULL,
c8 TINYINT UNSIGNED NOT NULL,
c9 TINYINT UNSIGNED NOT NULL
) ENGINE=MEMORY;

INSERT INTO positions_memory (c1, c2, c3, c4, c5, c6, c7, c8, c9)
SELECT c1, c2, c3, c4, c5, c6, c7, c8, c9 FROM positions;

CREATE INDEX i12 ON positions_memory(c1, c2) USING HASH; CREATE INDEX i13 ON positions_memory(c1, c3) USING HASH;
CREATE INDEX i14 ON positions_memory(c1, c4) USING HASH; CREATE INDEX i15 ON positions_memory(c1, c5) USING HASH;
CREATE INDEX i16 ON positions_memory(c1, c6) USING HASH; CREATE INDEX i17 ON positions_memory(c1, c7) USING HASH;
CREATE INDEX i18 ON positions_memory(c1, c8) USING HASH; CREATE INDEX i19 ON positions_memory(c1, c9) USING HASH;
CREATE INDEX i23 ON positions_memory(c2, c3) USING HASH; CREATE INDEX i24 ON positions_memory(c2, c4) USING HASH;
CREATE INDEX i25 ON positions_memory(c2, c5) USING HASH; CREATE INDEX i26 ON positions_memory(c2, c6) USING HASH;
CREATE INDEX i27 ON positions_memory(c2, c7) USING HASH; CREATE INDEX i28 ON positions_memory(c2, c8) USING HASH;
CREATE INDEX i29 ON positions_memory(c2, c9) USING HASH; CREATE INDEX i34 ON positions_memory(c3, c4) USING HASH;
CREATE INDEX i35 ON positions_memory(c3, c5) USING HASH; CREATE INDEX i36 ON positions_memory(c3, c6) USING HASH;
CREATE INDEX i37 ON positions_memory(c3, c7) USING HASH; CREATE INDEX i38 ON positions_memory(c3, c8) USING HASH;
CREATE INDEX i39 ON positions_memory(c3, c9) USING HASH; CREATE INDEX i45 ON positions_memory(c4, c5) USING HASH;
CREATE INDEX i46 ON positions_memory(c4, c6) USING HASH; CREATE INDEX i47 ON positions_memory(c4, c7) USING HASH;
CREATE INDEX i48 ON positions_memory(c4, c8) USING HASH; CREATE INDEX i49 ON positions_memory(c4, c9) USING HASH;
CREATE INDEX i56 ON positions_memory(c5, c6) USING HASH; CREATE INDEX i57 ON positions_memory(c5, c7) USING HASH;
CREATE INDEX i58 ON positions_memory(c5, c8) USING HASH; CREATE INDEX i59 ON positions_memory(c5, c9) USING HASH;
CREATE INDEX i67 ON positions_memory(c6, c7) USING HASH; CREATE INDEX i68 ON positions_memory(c6, c8) USING HASH;
CREATE INDEX i69 ON positions_memory(c6, c9) USING HASH; CREATE INDEX i78 ON positions_memory(c7, c8) USING HASH;
CREATE INDEX i79 ON positions_memory(c7, c9) USING HASH; CREATE INDEX i89 ON positions_memory(c8, c9) USING HASH;
CREATE INDEX i9 ON positions_memory(c9) USING HASH;
```

Maintenant, il s’agit de recréer les trois mêmes vues que nous avons créées pour le type de table MYISAM mais pour notre nouvelle table.

En premier lieu, la vue sur les rangées.

```USE sudoku;

DROP VIEW IF EXISTS sudoku_memory_rows_view;
CREATE VIEW sudoku_memory_rows_view AS
SELECT
r1.c1 as r1c1, r1.c2 as r1c2, r1.c3 as r1c3, r1.c4 as r1c4, r1.c5 as r1c5, r1.c6 as r1c6, r1.c7 as r1c7, r1.c8 as r1c8, r1.c9 as r1c9, r2.c1 as r2c1,
r2.c2 as r2c2, r2.c3 as r2c3, r2.c4 as r2c4, r2.c5 as r2c5, r2.c6 as r2c6, r2.c7 as r2c7, r2.c8 as r2c8, r2.c9 as r2c9, r3.c1 as r3c1, r3.c2 as r3c2,
r3.c3 as r3c3, r3.c4 as r3c4, r3.c5 as r3c5, r3.c6 as r3c6, r3.c7 as r3c7, r3.c8 as r3c8, r3.c9 as r3c9, r4.c1 as r4c1, r4.c2 as r4c2, r4.c3 as r4c3,
r4.c4 as r4c4, r4.c5 as r4c5, r4.c6 as r4c6, r4.c7 as r4c7, r4.c8 as r4c8, r4.c9 as r4c9, r5.c1 as r5c1, r5.c2 as r5c2, r5.c3 as r5c3, r5.c4 as r5c4,
r5.c5 as r5c5, r5.c6 as r5c6, r5.c7 as r5c7, r5.c8 as r5c8, r5.c9 as r5c9, r6.c1 as r6c1, r6.c2 as r6c2, r6.c3 as r6c3, r6.c4 as r6c4, r6.c5 as r6c5,
r6.c6 as r6c6, r6.c7 as r6c7, r6.c8 as r6c8, r6.c9 as r6c9, r7.c1 as r7c1, r7.c2 as r7c2, r7.c3 as r7c3, r7.c4 as r7c4, r7.c5 as r7c5, r7.c6 as r7c6,
r7.c7 as r7c7, r7.c8 as r7c8, r7.c9 as r7c9, r8.c1 as r8c1, r8.c2 as r8c2, r8.c3 as r8c3, r8.c4 as r8c4, r8.c5 as r8c5, r8.c6 as r8c6, r8.c7 as r8c7,
r8.c8 as r8c8, r8.c9 as r8c9, r9.c1 as r9c1, r9.c2 as r9c2, r9.c3 as r9c3, r9.c4 as r9c4, r9.c5 as r9c5, r9.c6 as r9c6, r9.c7 as r9c7, r9.c8 as r9c8,
r9.c9 as r9c9

FROM
positions_memory r1, positions_memory r2, positions_memory r3,
positions_memory r4, positions_memory r5, positions_memory r6,
positions_memory r7, positions_memory r8, positions_memory r9

WHERE
-- Nombres uniques dans chaque colonne
(r1.c1 <> r2.c1) AND (r1.c1 <> r3.c1) AND (r1.c1 <> r4.c1) AND (r1.c1 <> r5.c1) AND (r1.c1 <> r6.c1) AND (r1.c1 <> r7.c1) AND (r1.c1 <> r8.c1) AND (r1.c1 <> r9.c1) AND (r1.c2 <> r2.c2) AND (r1.c2 <> r3.c2) AND (r1.c2 <> r4.c2) AND (r1.c2 <> r5.c2) AND (r1.c2 <> r6.c2) AND (r1.c2 <> r7.c2) AND (r1.c2 <> r8.c2) AND (r1.c2 <> r9.c2) AND
(r1.c3 <> r2.c3) AND (r1.c3 <> r3.c3) AND (r1.c3 <> r4.c3) AND (r1.c3 <> r5.c3) AND (r1.c3 <> r6.c3) AND (r1.c3 <> r7.c3) AND (r1.c3 <> r8.c3) AND (r1.c3 <> r9.c3) AND (r1.c4 <> r2.c4) AND (r1.c4 <> r3.c4) AND (r1.c4 <> r4.c4) AND (r1.c4 <> r5.c4) AND (r1.c4 <> r6.c4) AND (r1.c4 <> r7.c4) AND (r1.c4 <> r8.c4) AND (r1.c4 <> r9.c4) AND
(r1.c5 <> r2.c5) AND (r1.c5 <> r3.c5) AND (r1.c5 <> r4.c5) AND (r1.c5 <> r5.c5) AND (r1.c5 <> r6.c5) AND (r1.c5 <> r7.c5) AND (r1.c5 <> r8.c5) AND (r1.c5 <> r9.c5) AND (r1.c6 <> r2.c6) AND (r1.c6 <> r3.c6) AND (r1.c6 <> r4.c6) AND (r1.c6 <> r5.c6) AND (r1.c6 <> r6.c6) AND (r1.c6 <> r7.c6) AND (r1.c6 <> r8.c6) AND (r1.c6 <> r9.c6) AND
(r1.c7 <> r2.c7) AND (r1.c7 <> r3.c7) AND (r1.c7 <> r4.c7) AND (r1.c7 <> r5.c7) AND (r1.c7 <> r6.c7) AND (r1.c7 <> r7.c7) AND (r1.c7 <> r8.c7) AND (r1.c7 <> r9.c7) AND (r1.c8 <> r2.c8) AND (r1.c8 <> r3.c8) AND (r1.c8 <> r4.c8) AND (r1.c8 <> r5.c8) AND (r1.c8 <> r6.c8) AND (r1.c8 <> r7.c8) AND (r1.c8 <> r8.c8) AND (r1.c8 <> r9.c8) AND
(r1.c9 <> r2.c9) AND (r1.c9 <> r3.c9) AND (r1.c9 <> r4.c9) AND (r1.c9 <> r5.c9) AND (r1.c9 <> r6.c9) AND (r1.c9 <> r7.c9) AND (r1.c9 <> r8.c9) AND (r1.c9 <> r9.c9) AND (r2.c1 <> r3.c1) AND (r2.c1 <> r4.c1) AND (r2.c1 <> r5.c1) AND (r2.c1 <> r6.c1) AND (r2.c1 <> r7.c1) AND (r2.c1 <> r8.c1) AND (r2.c1 <> r9.c1) AND (r2.c2 <> r3.c2) AND
(r2.c2 <> r4.c2) AND (r2.c2 <> r5.c2) AND (r2.c2 <> r6.c2) AND (r2.c2 <> r7.c2) AND (r2.c2 <> r8.c2) AND (r2.c2 <> r9.c2) AND (r2.c3 <> r3.c3) AND (r2.c3 <> r4.c3) AND (r2.c3 <> r5.c3) AND (r2.c3 <> r6.c3) AND (r2.c3 <> r7.c3) AND (r2.c3 <> r8.c3) AND (r2.c3 <> r9.c3) AND (r2.c4 <> r3.c4) AND (r2.c4 <> r4.c4) AND (r2.c4 <> r5.c4) AND
(r2.c4 <> r6.c4) AND (r2.c4 <> r7.c4) AND (r2.c4 <> r8.c4) AND (r2.c4 <> r9.c4) AND (r2.c5 <> r3.c5) AND (r2.c5 <> r4.c5) AND (r2.c5 <> r5.c5) AND (r2.c5 <> r6.c5) AND (r2.c5 <> r7.c5) AND (r2.c5 <> r8.c5) AND (r2.c5 <> r9.c5) AND (r2.c6 <> r3.c6) AND (r2.c6 <> r4.c6) AND (r2.c6 <> r5.c6) AND (r2.c6 <> r6.c6) AND (r2.c6 <> r7.c6) AND
(r2.c6 <> r8.c6) AND (r2.c6 <> r9.c6) AND (r2.c7 <> r3.c7) AND (r2.c7 <> r4.c7) AND (r2.c7 <> r5.c7) AND (r2.c7 <> r6.c7) AND (r2.c7 <> r7.c7) AND (r2.c7 <> r8.c7) AND (r2.c7 <> r9.c7) AND (r2.c8 <> r3.c8) AND (r2.c8 <> r4.c8) AND (r2.c8 <> r5.c8) AND (r2.c8 <> r6.c8) AND (r2.c8 <> r7.c8) AND (r2.c8 <> r8.c8) AND (r2.c8 <> r9.c8) AND
(r2.c9 <> r3.c9) AND (r2.c9 <> r4.c9) AND (r2.c9 <> r5.c9) AND (r2.c9 <> r6.c9) AND (r2.c9 <> r7.c9) AND (r2.c9 <> r8.c9) AND (r2.c9 <> r9.c9) AND (r3.c1 <> r4.c1) AND (r3.c1 <> r5.c1) AND (r3.c1 <> r6.c1) AND (r3.c1 <> r7.c1) AND (r3.c1 <> r8.c1) AND (r3.c1 <> r9.c1) AND (r3.c2 <> r4.c2) AND (r3.c2 <> r5.c2) AND (r3.c2 <> r6.c2) AND
(r3.c2 <> r7.c2) AND (r3.c2 <> r8.c2) AND (r3.c2 <> r9.c2) AND (r3.c3 <> r4.c3) AND (r3.c3 <> r5.c3) AND (r3.c3 <> r6.c3) AND (r3.c3 <> r7.c3) AND (r3.c3 <> r8.c3) AND (r3.c3 <> r9.c3) AND (r3.c4 <> r4.c4) AND (r3.c4 <> r5.c4) AND (r3.c4 <> r6.c4) AND (r3.c4 <> r7.c4) AND (r3.c4 <> r8.c4) AND (r3.c4 <> r9.c4) AND (r3.c5 <> r4.c5) AND
(r3.c5 <> r5.c5) AND (r3.c5 <> r6.c5) AND (r3.c5 <> r7.c5) AND (r3.c5 <> r8.c5) AND (r3.c5 <> r9.c5) AND (r3.c6 <> r4.c6) AND (r3.c6 <> r5.c6) AND (r3.c6 <> r6.c6) AND (r3.c6 <> r7.c6) AND (r3.c6 <> r8.c6) AND (r3.c6 <> r9.c6) AND (r3.c7 <> r4.c7) AND (r3.c7 <> r5.c7) AND (r3.c7 <> r6.c7) AND (r3.c7 <> r7.c7) AND (r3.c7 <> r8.c7) AND
(r3.c7 <> r9.c7) AND (r3.c8 <> r4.c8) AND (r3.c8 <> r5.c8) AND (r3.c8 <> r6.c8) AND (r3.c8 <> r7.c8) AND (r3.c8 <> r8.c8) AND (r3.c8 <> r9.c8) AND (r3.c9 <> r4.c9) AND (r3.c9 <> r5.c9) AND (r3.c9 <> r6.c9) AND (r3.c9 <> r7.c9) AND (r3.c9 <> r8.c9) AND (r3.c9 <> r9.c9) AND (r4.c1 <> r5.c1) AND (r4.c1 <> r6.c1) AND (r4.c1 <> r7.c1) AND
(r4.c1 <> r8.c1) AND (r4.c1 <> r9.c1) AND (r4.c2 <> r5.c2) AND (r4.c2 <> r6.c2) AND (r4.c2 <> r7.c2) AND (r4.c2 <> r8.c2) AND (r4.c2 <> r9.c2) AND (r4.c3 <> r5.c3) AND (r4.c3 <> r6.c3) AND (r4.c3 <> r7.c3) AND (r4.c3 <> r8.c3) AND (r4.c3 <> r9.c3) AND (r4.c4 <> r5.c4) AND (r4.c4 <> r6.c4) AND (r4.c4 <> r7.c4) AND (r4.c4 <> r8.c4) AND
(r4.c4 <> r9.c4) AND (r4.c5 <> r5.c5) AND (r4.c5 <> r6.c5) AND (r4.c5 <> r7.c5) AND (r4.c5 <> r8.c5) AND (r4.c5 <> r9.c5) AND (r4.c6 <> r5.c6) AND (r4.c6 <> r6.c6) AND (r4.c6 <> r7.c6) AND (r4.c6 <> r8.c6) AND (r4.c6 <> r9.c6) AND (r4.c7 <> r5.c7) AND (r4.c7 <> r6.c7) AND (r4.c7 <> r7.c7) AND (r4.c7 <> r8.c7) AND (r4.c7 <> r9.c7) AND
(r4.c8 <> r5.c8) AND (r4.c8 <> r6.c8) AND (r4.c8 <> r7.c8) AND (r4.c8 <> r8.c8) AND (r4.c8 <> r9.c8) AND (r4.c9 <> r5.c9) AND (r4.c9 <> r6.c9) AND (r4.c9 <> r7.c9) AND (r4.c9 <> r8.c9) AND (r4.c9 <> r9.c9) AND (r5.c1 <> r6.c1) AND (r5.c1 <> r7.c1) AND (r5.c1 <> r8.c1) AND (r5.c1 <> r9.c1) AND (r5.c2 <> r6.c2) AND (r5.c2 <> r7.c2) AND
(r5.c2 <> r8.c2) AND (r5.c2 <> r9.c2) AND (r5.c3 <> r6.c3) AND (r5.c3 <> r7.c3) AND (r5.c3 <> r8.c3) AND (r5.c3 <> r9.c3) AND (r5.c4 <> r6.c4) AND (r5.c4 <> r7.c4) AND (r5.c4 <> r8.c4) AND (r5.c4 <> r9.c4) AND (r5.c5 <> r6.c5) AND (r5.c5 <> r7.c5) AND (r5.c5 <> r8.c5) AND (r5.c5 <> r9.c5) AND (r5.c6 <> r6.c6) AND (r5.c6 <> r7.c6) AND
(r5.c6 <> r8.c6) AND (r5.c6 <> r9.c6) AND (r5.c7 <> r6.c7) AND (r5.c7 <> r7.c7) AND (r5.c7 <> r8.c7) AND (r5.c7 <> r9.c7) AND (r5.c8 <> r6.c8) AND (r5.c8 <> r7.c8) AND (r5.c8 <> r8.c8) AND (r5.c8 <> r9.c8) AND (r5.c9 <> r6.c9) AND (r5.c9 <> r7.c9) AND (r5.c9 <> r8.c9) AND (r5.c9 <> r9.c9) AND (r6.c1 <> r7.c1) AND (r6.c1 <> r8.c1) AND
(r6.c1 <> r9.c1) AND (r6.c2 <> r7.c2) AND (r6.c2 <> r8.c2) AND (r6.c2 <> r9.c2) AND (r6.c3 <> r7.c3) AND (r6.c3 <> r8.c3) AND (r6.c3 <> r9.c3) AND (r6.c4 <> r7.c4) AND (r6.c4 <> r8.c4) AND (r6.c4 <> r9.c4) AND (r6.c5 <> r7.c5) AND (r6.c5 <> r8.c5) AND (r6.c5 <> r9.c5) AND (r6.c6 <> r7.c6) AND (r6.c6 <> r8.c6) AND (r6.c6 <> r9.c6) AND
(r6.c7 <> r7.c7) AND (r6.c7 <> r8.c7) AND (r6.c7 <> r9.c7) AND (r6.c8 <> r7.c8) AND (r6.c8 <> r8.c8) AND (r6.c8 <> r9.c8) AND (r6.c9 <> r7.c9) AND (r6.c9 <> r8.c9) AND (r6.c9 <> r9.c9) AND (r7.c1 <> r8.c1) AND (r7.c1 <> r9.c1) AND (r7.c2 <> r8.c2) AND (r7.c2 <> r9.c2) AND (r7.c3 <> r8.c3) AND (r7.c3 <> r9.c3) AND (r7.c4 <> r8.c4) AND
(r7.c4 <> r9.c4) AND (r7.c5 <> r8.c5) AND (r7.c5 <> r9.c5) AND (r7.c6 <> r8.c6) AND (r7.c6 <> r9.c6) AND (r7.c7 <> r8.c7) AND (r7.c7 <> r9.c7) AND (r7.c8 <> r8.c8) AND (r7.c8 <> r9.c8) AND (r7.c9 <> r8.c9) AND (r7.c9 <> r9.c9) AND (r8.c1 <> r9.c1) AND (r8.c2 <> r9.c2) AND (r8.c3 <> r9.c3) AND (r8.c4 <> r9.c4) AND (r8.c5 <> r9.c5) AND
(r8.c6 <> r9.c6) AND (r8.c7 <> r9.c7) AND (r8.c8 <> r9.c8) AND (r8.c9 <> r9.c9) AND
-- Nombres uniques dans chaque maison de 3x3
(r1.c1 <> r2.c2) AND (r1.c1 <> r2.c3) AND (r1.c1 <> r3.c2) AND (r1.c1 <> r3.c3) AND (r1.c2 <> r2.c1) AND (r1.c2 <> r2.c3) AND (r1.c2 <> r3.c1) AND (r1.c2 <> r3.c3) AND (r1.c3 <> r2.c1) AND (r1.c3 <> r2.c2) AND (r1.c3 <> r3.c1) AND (r1.c3 <> r3.c2) AND (r1.c4 <> r2.c5) AND (r1.c4 <> r2.c6) AND (r1.c4 <> r3.c5) AND (r1.c4 <> r3.c6) AND
(r1.c5 <> r2.c4) AND (r1.c5 <> r2.c6) AND (r1.c5 <> r3.c4) AND (r1.c5 <> r3.c6) AND (r1.c6 <> r2.c4) AND (r1.c6 <> r2.c5) AND (r1.c6 <> r3.c4) AND (r1.c6 <> r3.c5) AND (r1.c7 <> r2.c8) AND (r1.c7 <> r2.c9) AND (r1.c7 <> r3.c8) AND (r1.c7 <> r3.c9) AND (r1.c8 <> r2.c7) AND (r1.c8 <> r2.c9) AND (r1.c8 <> r3.c7) AND (r1.c8 <> r3.c9) AND
(r1.c9 <> r2.c7) AND (r1.c9 <> r2.c8) AND (r1.c9 <> r3.c7) AND (r1.c9 <> r3.c8) AND (r2.c1 <> r3.c2) AND (r2.c1 <> r3.c3) AND (r2.c2 <> r3.c1) AND (r2.c2 <> r3.c3) AND (r2.c3 <> r3.c1) AND (r2.c3 <> r3.c2) AND (r2.c4 <> r3.c5) AND (r2.c4 <> r3.c6) AND (r2.c5 <> r3.c4) AND (r2.c5 <> r3.c6) AND (r2.c6 <> r3.c4) AND (r2.c6 <> r3.c5) AND
(r2.c7 <> r3.c8) AND (r2.c7 <> r3.c9) AND (r2.c8 <> r3.c7) AND (r2.c8 <> r3.c9) AND (r2.c9 <> r3.c7) AND (r2.c9 <> r3.c8) AND (r4.c1 <> r5.c2) AND (r4.c1 <> r5.c3) AND (r4.c1 <> r6.c2) AND (r4.c1 <> r6.c3) AND (r4.c2 <> r5.c1) AND (r4.c2 <> r5.c3) AND (r4.c2 <> r6.c1) AND (r4.c2 <> r6.c3) AND (r4.c3 <> r5.c1) AND (r4.c3 <> r5.c2) AND
(r4.c3 <> r6.c1) AND (r4.c3 <> r6.c2) AND (r4.c4 <> r5.c5) AND (r4.c4 <> r5.c6) AND (r4.c4 <> r6.c5) AND (r4.c4 <> r6.c6) AND (r4.c5 <> r5.c4) AND (r4.c5 <> r5.c6) AND (r4.c5 <> r6.c4) AND (r4.c5 <> r6.c6) AND (r4.c6 <> r5.c4) AND (r4.c6 <> r5.c5) AND (r4.c6 <> r6.c4) AND (r4.c6 <> r6.c5) AND (r4.c7 <> r5.c8) AND (r4.c7 <> r5.c9) AND
(r4.c7 <> r6.c8) AND (r4.c7 <> r6.c9) AND (r4.c8 <> r5.c7) AND (r4.c8 <> r5.c9) AND (r4.c8 <> r6.c7) AND (r4.c8 <> r6.c9) AND (r4.c9 <> r5.c7) AND (r4.c9 <> r5.c8) AND (r4.c9 <> r6.c7) AND (r4.c9 <> r6.c8) AND (r5.c1 <> r6.c2) AND (r5.c1 <> r6.c3) AND (r5.c2 <> r6.c1) AND (r5.c2 <> r6.c3) AND (r5.c3 <> r6.c1) AND (r5.c3 <> r6.c2) AND
(r5.c4 <> r6.c5) AND (r5.c4 <> r6.c6) AND (r5.c5 <> r6.c4) AND (r5.c5 <> r6.c6) AND (r5.c6 <> r6.c4) AND (r5.c6 <> r6.c5) AND (r5.c7 <> r6.c8) AND (r5.c7 <> r6.c9) AND (r5.c8 <> r6.c7) AND (r5.c8 <> r6.c9) AND (r5.c9 <> r6.c7) AND (r5.c9 <> r6.c8) AND (r7.c1 <> r8.c2) AND (r7.c1 <> r8.c3) AND (r7.c1 <> r9.c2) AND (r7.c1 <> r9.c3) AND
(r7.c2 <> r8.c1) AND (r7.c2 <> r8.c3) AND (r7.c2 <> r9.c1) AND (r7.c2 <> r9.c3) AND (r7.c3 <> r8.c1) AND (r7.c3 <> r8.c2) AND (r7.c3 <> r9.c1) AND (r7.c3 <> r9.c2) AND (r7.c4 <> r8.c5) AND (r7.c4 <> r8.c6) AND (r7.c4 <> r9.c5) AND (r7.c4 <> r9.c6) AND (r7.c5 <> r8.c4) AND (r7.c5 <> r8.c6) AND (r7.c5 <> r9.c4) AND (r7.c5 <> r9.c6) AND
(r7.c6 <> r8.c4) AND (r7.c6 <> r8.c5) AND (r7.c6 <> r9.c4) AND (r7.c6 <> r9.c5) AND (r7.c7 <> r8.c8) AND (r7.c7 <> r8.c9) AND (r7.c7 <> r9.c8) AND (r7.c7 <> r9.c9) AND (r7.c8 <> r8.c7) AND (r7.c8 <> r8.c9) AND (r7.c8 <> r9.c7) AND (r7.c8 <> r9.c9) AND (r7.c9 <> r8.c7) AND (r7.c9 <> r8.c8) AND (r7.c9 <> r9.c7) AND (r7.c9 <> r9.c8) AND
(r8.c1 <> r9.c2) AND (r8.c1 <> r9.c3) AND (r8.c2 <> r9.c1) AND (r8.c2 <> r9.c3) AND (r8.c3 <> r9.c1) AND (r8.c3 <> r9.c2) AND (r8.c4 <> r9.c5) AND (r8.c4 <> r9.c6) AND (r8.c5 <> r9.c4) AND (r8.c5 <> r9.c6) AND (r8.c6 <> r9.c4) AND (r8.c6 <> r9.c5) AND (r8.c7 <> r9.c8) AND (r8.c7 <> r9.c9) AND (r8.c8 <> r9.c7) AND (r8.c8 <> r9.c9) AND
(r8.c9 <> r9.c7) AND (r8.c9 <> r9.c8);
```

En second lieu, la vue sur les colonnes.

```USE sudoku;

DROP VIEW IF EXISTS sudoku_memory_columns_view;
CREATE VIEW sudoku_memory_columns_view AS
SELECT
col1.c1 as r1c1, col1.c2 as r2c1, col1.c3 as r3c1, col1.c4 as r4c1, col1.c5 as r5c1,col1.c6 as r6c1, col1.c7 as r7c1, col1.c8 as r8c1, col1.c9 as r9c1, col2.c1 as r1c2,
col2.c2 as r2c2, col2.c3 as r3c2, col2.c4 as r4c2, col2.c5 as r5c2, col2.c6 as r6c2,col2.c7 as r7c2, col2.c8 as r8c2, col2.c9 as r9c2, col3.c1 as r1c3, col3.c2 as r2c3,
col3.c3 as r3c3, col3.c4 as r4c3, col3.c5 as r5c3, col3.c6 as r6c3, col3.c7 as r7c3,col3.c8 as r8c3, col3.c9 as r9c3, col4.c1 as r1c4, col4.c2 as r2c4, col4.c3 as r3c4,
col4.c4 as r4c4, col4.c5 as r5c4, col4.c6 as r6c4, col4.c7 as r7c4, col4.c8 as r8c4,col4.c9 as r9c4, col5.c1 as r1c5, col5.c2 as r2c5, col5.c3 as r3c5, col5.c4 as r4c5,
col5.c5 as r5c5, col5.c6 as r6c5, col5.c7 as r7c5, col5.c8 as r8c5, col5.c9 as r9c5,col6.c1 as r1c6, col6.c2 as r2c6, col6.c3 as r3c6, col6.c4 as r4c6, col6.c5 as r5c6,
col6.c6 as r6c6, col6.c7 as r7c6, col6.c8 as r8c6, col6.c9 as r9c6, col7.c1 as r1c7,col7.c2 as r2c7, col7.c3 as r3c7, col7.c4 as r4c7, col7.c5 as r5c7, col7.c6 as r6c7,
col7.c7 as r7c7, col7.c8 as r8c7, col7.c9 as r9c7, col8.c1 as r1c8, col8.c2 as r2c8,col8.c3 as r3c8, col8.c4 as r4c8, col8.c5 as r5c8, col8.c6 as r6c8, col8.c7 as r7c8,
col8.c8 as r8c8, col8.c9 as r9c8, col9.c1 as r1c9, col9.c2 as r2c9, col9.c3 as r3c9,col9.c4 as r4c9, col9.c5 as r5c9, col9.c6 as r6c9, col9.c7 as r7c9, col9.c8 as r8c9,
col9.c9 as r9c9
FROM
positions_memory col1, positions_memory col2, positions_memory col3, positions_memory col4,
positions_memory col5, positions_memory col6, positions_memory col7, positions_memory col8, positions_memory col9
WHERE
-- Nombres uniques dans chaque rangee
(col1.c1 <> col2.c1) AND (col1.c1 <> col3.c1) AND (col1.c1 <> col4.c1) AND (col1.c1 <> col5.c1) AND (col1.c1 <> col6.c1) AND (col1.c1 <> col7.c1) AND (col1.c1 <> col8.c1) AND (col1.c1 <> col9.c1) AND (col1.c2 <> col2.c2) AND (col1.c2 <> col3.c2) AND (col1.c2 <> col4.c2) AND (col1.c2 <> col5.c2) AND (col1.c2 <> col6.c2) AND (col1.c2 <> col7.c2) AND (col1.c2 <> col8.c2) AND (col1.c2 <> col9.c2) AND (col1.c3 <> col2.c3) AND (col1.c3 <> col3.c3) AND (col1.c3 <> col4.c3) AND (col1.c3 <> col5.c3) AND (col1.c3 <> col6.c3) AND (col1.c3 <> col7.c3) AND (col1.c3 <> col8.c3) AND (col1.c3 <> col9.c3) AND (col1.c4 <> col2.c4) AND (col1.c4 <> col3.c4) AND (col1.c4 <> col4.c4) AND (col1.c4 <> col5.c4) AND (col1.c4 <> col6.c4) AND (col1.c4 <> col7.c4) AND (col1.c4 <> col8.c4) AND (col1.c4 <> col9.c4) AND
(col1.c5 <> col2.c5) AND (col1.c5 <> col3.c5) AND (col1.c5 <> col4.c5) AND (col1.c5 <> col5.c5) AND (col1.c5 <> col6.c5) AND (col1.c5 <> col7.c5) AND (col1.c5 <> col8.c5) AND (col1.c5 <> col9.c5) AND (col1.c6 <> col2.c6) AND (col1.c6 <> col3.c6) AND (col1.c6 <> col4.c6) AND (col1.c6 <> col5.c6) AND (col1.c6 <> col6.c6) AND (col1.c6 <> col7.c6) AND (col1.c6 <> col8.c6) AND (col1.c6 <> col9.c6) AND (col1.c7 <> col2.c7) AND (col1.c7 <> col3.c7) AND (col1.c7 <> col4.c7) AND (col1.c7 <> col5.c7) AND (col1.c7 <> col6.c7) AND (col1.c7 <> col7.c7) AND (col1.c7 <> col8.c7) AND (col1.c7 <> col9.c7) AND (col1.c8 <> col2.c8) AND (col1.c8 <> col3.c8) AND (col1.c8 <> col4.c8) AND (col1.c8 <> col5.c8) AND (col1.c8 <> col6.c8) AND (col1.c8 <> col7.c8) AND (col1.c8 <> col8.c8) AND (col1.c8 <> col9.c8) AND
(col1.c9 <> col2.c9) AND (col1.c9 <> col3.c9) AND (col1.c9 <> col4.c9) AND (col1.c9 <> col5.c9) AND (col1.c9 <> col6.c9) AND (col1.c9 <> col7.c9) AND (col1.c9 <> col8.c9) AND (col1.c9 <> col9.c9) AND (col2.c1 <> col3.c1) AND (col2.c1 <> col4.c1) AND (col2.c1 <> col5.c1) AND (col2.c1 <> col6.c1) AND (col2.c1 <> col7.c1) AND (col2.c1 <> col8.c1) AND (col2.c1 <> col9.c1) AND (col2.c2 <> col3.c2) AND (col2.c2 <> col4.c2) AND (col2.c2 <> col5.c2) AND (col2.c2 <> col6.c2) AND (col2.c2 <> col7.c2) AND (col2.c2 <> col8.c2) AND (col2.c2 <> col9.c2) AND (col2.c3 <> col3.c3) AND (col2.c3 <> col4.c3) AND (col2.c3 <> col5.c3) AND (col2.c3 <> col6.c3) AND (col2.c3 <> col7.c3) AND (col2.c3 <> col8.c3) AND (col2.c3 <> col9.c3) AND (col2.c4 <> col3.c4) AND (col2.c4 <> col4.c4) AND (col2.c4 <> col5.c4) AND
(col2.c4 <> col6.c4) AND (col2.c4 <> col7.c4) AND (col2.c4 <> col8.c4) AND (col2.c4 <> col9.c4) AND (col2.c5 <> col3.c5) AND (col2.c5 <> col4.c5) AND (col2.c5 <> col5.c5) AND (col2.c5 <> col6.c5) AND (col2.c5 <> col7.c5) AND (col2.c5 <> col8.c5) AND (col2.c5 <> col9.c5) AND (col2.c6 <> col3.c6) AND (col2.c6 <> col4.c6) AND (col2.c6 <> col5.c6) AND (col2.c6 <> col6.c6) AND (col2.c6 <> col7.c6) AND (col2.c6 <> col8.c6) AND (col2.c6 <> col9.c6) AND (col2.c7 <> col3.c7) AND (col2.c7 <> col4.c7) AND (col2.c7 <> col5.c7) AND (col2.c7 <> col6.c7) AND (col2.c7 <> col7.c7) AND (col2.c7 <> col8.c7) AND (col2.c7 <> col9.c7) AND (col2.c8 <> col3.c8) AND (col2.c8 <> col4.c8) AND (col2.c8 <> col5.c8) AND (col2.c8 <> col6.c8) AND (col2.c8 <> col7.c8) AND (col2.c8 <> col8.c8) AND (col2.c8 <> col9.c8) AND
(col2.c9 <> col3.c9) AND (col2.c9 <> col4.c9) AND (col2.c9 <> col5.c9) AND (col2.c9 <> col6.c9) AND (col2.c9 <> col7.c9) AND (col2.c9 <> col8.c9) AND (col2.c9 <> col9.c9) AND (col3.c1 <> col4.c1) AND (col3.c1 <> col5.c1) AND (col3.c1 <> col6.c1) AND (col3.c1 <> col7.c1) AND (col3.c1 <> col8.c1) AND (col3.c1 <> col9.c1) AND (col3.c2 <> col4.c2) AND (col3.c2 <> col5.c2) AND (col3.c2 <> col6.c2) AND (col3.c2 <> col7.c2) AND (col3.c2 <> col8.c2) AND (col3.c2 <> col9.c2) AND (col3.c3 <> col4.c3) AND (col3.c3 <> col5.c3) AND (col3.c3 <> col6.c3) AND (col3.c3 <> col7.c3) AND (col3.c3 <> col8.c3) AND (col3.c3 <> col9.c3) AND (col3.c4 <> col4.c4) AND (col3.c4 <> col5.c4) AND (col3.c4 <> col6.c4) AND (col3.c4 <> col7.c4) AND (col3.c4 <> col8.c4) AND (col3.c4 <> col9.c4) AND (col3.c5 <> col4.c5) AND
(col3.c5 <> col5.c5) AND (col3.c5 <> col6.c5) AND (col3.c5 <> col7.c5) AND (col3.c5 <> col8.c5) AND (col3.c5 <> col9.c5) AND (col3.c6 <> col4.c6) AND (col3.c6 <> col5.c6) AND (col3.c6 <> col6.c6) AND (col3.c6 <> col7.c6) AND (col3.c6 <> col8.c6) AND (col3.c6 <> col9.c6) AND (col3.c7 <> col4.c7) AND (col3.c7 <> col5.c7) AND (col3.c7 <> col6.c7) AND (col3.c7 <> col7.c7) AND (col3.c7 <> col8.c7) AND (col3.c7 <> col9.c7) AND (col3.c8 <> col4.c8) AND (col3.c8 <> col5.c8) AND (col3.c8 <> col6.c8) AND (col3.c8 <> col7.c8) AND (col3.c8 <> col8.c8) AND (col3.c8 <> col9.c8) AND (col3.c9 <> col4.c9) AND (col3.c9 <> col5.c9) AND (col3.c9 <> col6.c9) AND (col3.c9 <> col7.c9) AND (col3.c9 <> col8.c9) AND (col3.c9 <> col9.c9) AND (col4.c1 <> col5.c1) AND (col4.c1 <> col6.c1) AND (col4.c1 <> col7.c1) AND
(col4.c1 <> col8.c1) AND (col4.c1 <> col9.c1) AND (col4.c2 <> col5.c2) AND (col4.c2 <> col6.c2) AND (col4.c2 <> col7.c2) AND (col4.c2 <> col8.c2) AND (col4.c2 <> col9.c2) AND (col4.c3 <> col5.c3) AND (col4.c3 <> col6.c3) AND (col4.c3 <> col7.c3) AND (col4.c3 <> col8.c3) AND (col4.c3 <> col9.c3) AND (col4.c4 <> col5.c4) AND (col4.c4 <> col6.c4) AND (col4.c4 <> col7.c4) AND (col4.c4 <> col8.c4) AND (col4.c4 <> col9.c4) AND (col4.c5 <> col5.c5) AND (col4.c5 <> col6.c5) AND (col4.c5 <> col7.c5) AND (col4.c5 <> col8.c5) AND (col4.c5 <> col9.c5) AND (col4.c6 <> col5.c6) AND (col4.c6 <> col6.c6) AND (col4.c6 <> col7.c6) AND (col4.c6 <> col8.c6) AND (col4.c6 <> col9.c6) AND (col4.c7 <> col5.c7) AND (col4.c7 <> col6.c7) AND (col4.c7 <> col7.c7) AND (col4.c7 <> col8.c7) AND (col4.c7 <> col9.c7) AND
(col4.c8 <> col5.c8) AND (col4.c8 <> col6.c8) AND (col4.c8 <> col7.c8) AND (col4.c8 <> col8.c8) AND (col4.c8 <> col9.c8) AND (col4.c9 <> col5.c9) AND (col4.c9 <> col6.c9) AND (col4.c9 <> col7.c9) AND (col4.c9 <> col8.c9) AND (col4.c9 <> col9.c9) AND (col5.c1 <> col6.c1) AND (col5.c1 <> col7.c1) AND (col5.c1 <> col8.c1) AND (col5.c1 <> col9.c1) AND (col5.c2 <> col6.c2) AND (col5.c2 <> col7.c2) AND (col5.c2 <> col8.c2) AND (col5.c2 <> col9.c2) AND (col5.c3 <> col6.c3) AND (col5.c3 <> col7.c3) AND (col5.c3 <> col8.c3) AND (col5.c3 <> col9.c3) AND (col5.c4 <> col6.c4) AND (col5.c4 <> col7.c4) AND (col5.c4 <> col8.c4) AND (col5.c4 <> col9.c4) AND (col5.c5 <> col6.c5) AND (col5.c5 <> col7.c5) AND (col5.c5 <> col8.c5) AND (col5.c5 <> col9.c5) AND (col5.c6 <> col6.c6) AND (col5.c6 <> col7.c6) AND
(col5.c6 <> col8.c6) AND (col5.c6 <> col9.c6) AND (col5.c7 <> col6.c7) AND (col5.c7 <> col7.c7) AND (col5.c7 <> col8.c7) AND (col5.c7 <> col9.c7) AND (col5.c8 <> col6.c8) AND (col5.c8 <> col7.c8) AND (col5.c8 <> col8.c8) AND (col5.c8 <> col9.c8) AND (col5.c9 <> col6.c9) AND (col5.c9 <> col7.c9) AND (col5.c9 <> col8.c9) AND (col5.c9 <> col9.c9) AND (col6.c1 <> col7.c1) AND (col6.c1 <> col8.c1) AND (col6.c1 <> col9.c1) AND (col6.c2 <> col7.c2) AND (col6.c2 <> col8.c2) AND (col6.c2 <> col9.c2) AND (col6.c3 <> col7.c3) AND (col6.c3 <> col8.c3) AND (col6.c3 <> col9.c3) AND (col6.c4 <> col7.c4) AND (col6.c4 <> col8.c4) AND (col6.c4 <> col9.c4) AND (col6.c5 <> col7.c5) AND (col6.c5 <> col8.c5) AND (col6.c5 <> col9.c5) AND (col6.c6 <> col7.c6) AND (col6.c6 <> col8.c6) AND (col6.c6 <> col9.c6) AND
(col6.c7 <> col7.c7) AND (col6.c7 <> col8.c7) AND (col6.c7 <> col9.c7) AND (col6.c8 <> col7.c8) AND (col6.c8 <> col8.c8) AND (col6.c8 <> col9.c8) AND (col6.c9 <> col7.c9) AND (col6.c9 <> col8.c9) AND (col6.c9 <> col9.c9) AND (col7.c1 <> col8.c1) AND (col7.c1 <> col9.c1) AND (col7.c2 <> col8.c2) AND (col7.c2 <> col9.c2) AND (col7.c3 <> col8.c3) AND (col7.c3 <> col9.c3) AND (col7.c4 <> col8.c4) AND (col7.c4 <> col9.c4) AND (col7.c5 <> col8.c5) AND (col7.c5 <> col9.c5) AND (col7.c6 <> col8.c6) AND (col7.c6 <> col9.c6) AND (col7.c7 <> col8.c7) AND (col7.c7 <> col9.c7) AND (col7.c8 <> col8.c8) AND (col7.c8 <> col9.c8) AND (col7.c9 <> col8.c9) AND (col7.c9 <> col9.c9) AND (col8.c1 <> col9.c1) AND (col8.c2 <> col9.c2) AND (col8.c3 <> col9.c3) AND (col8.c4 <> col9.c4) AND (col8.c5 <> col9.c5) AND
(col8.c6 <> col9.c6) AND (col8.c7 <> col9.c7) AND (col8.c8 <> col9.c8) AND (col8.c9 <> col9.c9) AND
-- Nombres uniques dans chaque maison de 3x3
(col1.c1 <> col1.c2) AND (col1.c1 <> col1.c3) AND (col1.c1 <> col2.c2) AND (col1.c1 <> col2.c3) AND (col1.c1 <> col3.c2) AND (col1.c1 <> col3.c3) AND (col1.c2 <> col1.c3) AND (col1.c2 <> col2.c1) AND (col1.c2 <> col2.c3) AND (col1.c2 <> col3.c1) AND (col1.c2 <> col3.c3) AND (col1.c3 <> col2.c1) AND (col1.c3 <> col2.c2) AND (col1.c3 <> col3.c1) AND (col1.c3 <> col3.c2) AND (col1.c4 <> col1.c5) AND (col1.c4 <> col1.c6) AND (col1.c4 <> col2.c5) AND (col1.c4 <> col2.c6) AND (col1.c4 <> col3.c5) AND (col1.c4 <> col3.c6) AND (col1.c5 <> col1.c6) AND (col1.c5 <> col2.c4) AND (col1.c5 <> col2.c6) AND (col1.c5 <> col3.c4) AND (col1.c5 <> col3.c6) AND (col1.c6 <> col2.c4) AND (col1.c6 <> col2.c5) AND (col1.c6 <> col3.c4) AND (col1.c6 <> col3.c5) AND (col1.c7 <> col1.c8) AND (col1.c7 <> col1.c9) AND
(col1.c7 <> col2.c8) AND (col1.c7 <> col2.c9) AND (col1.c7 <> col3.c8) AND (col1.c7 <> col3.c9) AND (col1.c8 <> col1.c9) AND (col1.c8 <> col2.c7) AND (col1.c8 <> col2.c9) AND (col1.c8 <> col3.c7) AND (col1.c8 <> col3.c9) AND (col1.c9 <> col2.c7) AND (col1.c9 <> col2.c8) AND (col1.c9 <> col3.c7) AND (col1.c9 <> col3.c8) AND (col2.c1 <> col2.c2) AND (col2.c1 <> col2.c3) AND (col2.c1 <> col3.c2) AND (col2.c1 <> col3.c3) AND (col2.c2 <> col2.c3) AND (col2.c2 <> col3.c1) AND (col2.c2 <> col3.c3) AND (col2.c3 <> col3.c1) AND (col2.c3 <> col3.c2) AND (col2.c4 <> col2.c5) AND (col2.c4 <> col2.c6) AND (col2.c4 <> col3.c5) AND (col2.c4 <> col3.c6) AND (col2.c5 <> col2.c6) AND (col2.c5 <> col3.c4) AND (col2.c5 <> col3.c6) AND (col2.c6 <> col3.c4) AND (col2.c6 <> col3.c5) AND (col2.c7 <> col2.c8) AND
(col2.c7 <> col2.c9) AND (col2.c7 <> col3.c8) AND (col2.c7 <> col3.c9) AND (col2.c8 <> col2.c9) AND (col2.c8 <> col3.c7) AND (col2.c8 <> col3.c9) AND (col2.c9 <> col3.c7) AND (col2.c9 <> col3.c8) AND (col3.c1 <> col3.c2) AND (col3.c1 <> col3.c3) AND (col3.c2 <> col3.c3) AND (col3.c4 <> col3.c5) AND (col3.c4 <> col3.c6) AND (col3.c5 <> col3.c6) AND (col3.c7 <> col3.c8) AND (col3.c7 <> col3.c9) AND (col3.c8 <> col3.c9) AND (col4.c1 <> col4.c2) AND (col4.c1 <> col4.c3) AND (col4.c1 <> col5.c2) AND (col4.c1 <> col5.c3) AND (col4.c1 <> col6.c2) AND (col4.c1 <> col6.c3) AND (col4.c2 <> col4.c3) AND (col4.c2 <> col5.c1) AND (col4.c2 <> col5.c3) AND (col4.c2 <> col6.c1) AND (col4.c2 <> col6.c3) AND (col4.c3 <> col5.c1) AND (col4.c3 <> col5.c2) AND (col4.c3 <> col6.c1) AND (col4.c3 <> col6.c2) AND
(col4.c4 <> col4.c5) AND (col4.c4 <> col4.c6) AND (col4.c4 <> col5.c5) AND (col4.c4 <> col5.c6) AND (col4.c4 <> col6.c5) AND (col4.c4 <> col6.c6) AND (col4.c5 <> col4.c6) AND (col4.c5 <> col5.c4) AND (col4.c5 <> col5.c6) AND (col4.c5 <> col6.c4) AND (col4.c5 <> col6.c6) AND (col4.c6 <> col5.c4) AND (col4.c6 <> col5.c5) AND (col4.c6 <> col6.c4) AND (col4.c6 <> col6.c5) AND (col4.c7 <> col4.c8) AND (col4.c7 <> col4.c9) AND (col4.c7 <> col5.c8) AND (col4.c7 <> col5.c9) AND (col4.c7 <> col6.c8) AND (col4.c7 <> col6.c9) AND (col4.c8 <> col4.c9) AND (col4.c8 <> col5.c7) AND (col4.c8 <> col5.c9) AND (col4.c8 <> col6.c7) AND (col4.c8 <> col6.c9) AND (col4.c9 <> col5.c7) AND (col4.c9 <> col5.c8) AND (col4.c9 <> col6.c7) AND (col4.c9 <> col6.c8) AND (col5.c1 <> col5.c2) AND (col5.c1 <> col5.c3) AND
(col5.c1 <> col6.c2) AND (col5.c1 <> col6.c3) AND (col5.c2 <> col5.c3) AND (col5.c2 <> col6.c1) AND (col5.c2 <> col6.c3) AND (col5.c3 <> col6.c1) AND (col5.c3 <> col6.c2) AND (col5.c4 <> col5.c5) AND (col5.c4 <> col5.c6) AND (col5.c4 <> col6.c5) AND (col5.c4 <> col6.c6) AND (col5.c5 <> col5.c6) AND (col5.c5 <> col6.c4) AND (col5.c5 <> col6.c6) AND (col5.c6 <> col6.c4) AND (col5.c6 <> col6.c5) AND (col5.c7 <> col5.c8) AND (col5.c7 <> col5.c9) AND (col5.c7 <> col6.c8) AND (col5.c7 <> col6.c9) AND (col5.c8 <> col5.c9) AND (col5.c8 <> col6.c7) AND (col5.c8 <> col6.c9) AND (col5.c9 <> col6.c7) AND (col5.c9 <> col6.c8) AND (col6.c1 <> col6.c2) AND (col6.c1 <> col6.c3) AND (col6.c2 <> col6.c3) AND (col6.c4 <> col6.c5) AND (col6.c4 <> col6.c6) AND (col6.c5 <> col6.c6) AND (col6.c7 <> col6.c8) AND
(col6.c7 <> col6.c9) AND (col6.c8 <> col6.c9) AND (col7.c1 <> col7.c2) AND (col7.c1 <> col7.c3) AND (col7.c1 <> col8.c2) AND (col7.c1 <> col8.c3) AND (col7.c1 <> col9.c2) AND (col7.c1 <> col9.c3) AND (col7.c2 <> col7.c3) AND (col7.c2 <> col8.c1) AND (col7.c2 <> col8.c3) AND (col7.c2 <> col9.c1) AND (col7.c2 <> col9.c3) AND (col7.c3 <> col8.c1) AND (col7.c3 <> col8.c2) AND (col7.c3 <> col9.c1) AND (col7.c3 <> col9.c2) AND (col7.c4 <> col7.c5) AND (col7.c4 <> col7.c6) AND (col7.c4 <> col8.c5) AND (col7.c4 <> col8.c6) AND (col7.c4 <> col9.c5) AND (col7.c4 <> col9.c6) AND (col7.c5 <> col7.c6) AND (col7.c5 <> col8.c4) AND (col7.c5 <> col8.c6) AND (col7.c5 <> col9.c4) AND (col7.c5 <> col9.c6) AND (col7.c6 <> col8.c4) AND (col7.c6 <> col8.c5) AND (col7.c6 <> col9.c4) AND (col7.c6 <> col9.c5) AND
(col7.c7 <> col7.c8) AND (col7.c7 <> col7.c9) AND (col7.c7 <> col8.c8) AND (col7.c7 <> col8.c9) AND (col7.c7 <> col9.c8) AND (col7.c7 <> col9.c9) AND (col7.c8 <> col7.c9) AND (col7.c8 <> col8.c7) AND (col7.c8 <> col8.c9) AND (col7.c8 <> col9.c7) AND (col7.c8 <> col9.c9) AND (col7.c9 <> col8.c7) AND (col7.c9 <> col8.c8) AND (col7.c9 <> col9.c7) AND (col7.c9 <> col9.c8) AND (col8.c1 <> col8.c2) AND (col8.c1 <> col8.c3) AND (col8.c1 <> col9.c2) AND (col8.c1 <> col9.c3) AND (col8.c2 <> col8.c3) AND (col8.c2 <> col9.c1) AND (col8.c2 <> col9.c3) AND (col8.c3 <> col9.c1) AND (col8.c3 <> col9.c2) AND (col8.c4 <> col8.c5) AND (col8.c4 <> col8.c6) AND (col8.c4 <> col9.c5) AND (col8.c4 <> col9.c6) AND (col8.c5 <> col8.c6) AND (col8.c5 <> col9.c4) AND (col8.c5 <> col9.c6) AND (col8.c6 <> col9.c4) AND
(col8.c6 <> col9.c5) AND (col8.c7 <> col8.c8) AND (col8.c7 <> col8.c9) AND (col8.c7 <> col9.c8) AND (col8.c7 <> col9.c9) AND (col8.c8 <> col8.c9) AND (col8.c8 <> col9.c7) AND (col8.c8 <> col9.c9) AND (col8.c9 <> col9.c7) AND (col8.c9 <> col9.c8) AND (col9.c1 <> col9.c2) AND (col9.c1 <> col9.c3) AND (col9.c2 <> col9.c3) AND (col9.c4 <> col9.c5) AND (col9.c4 <> col9.c6) AND (col9.c5 <> col9.c6) AND (col9.c7 <> col9.c8) AND (col9.c7 <> col9.c9) AND (col9.c8 <> col9.c9);
```

Finalement, la vue combinée.

```USE sudoku;

DROP VIEW IF EXISTS sudoku_memory_combined_view;
CREATE VIEW sudoku_memory_combined_view AS
SELECT t1.*
FROM sudoku_memory_rows_view t1
INNER JOIN sudoku_memory_columns_view t2
ON

-- Jointures entre représentation-colonnes et représentation-rangées
(t1.r1c1 = t2.r1c1) AND (t1.r1c2 = t2.r1c2) AND (t1.r1c3 = t2.r1c3) AND (t1.r1c4 = t2.r1c4) AND
(t1.r1c5 = t2.r1c5) AND (t1.r1c6 = t2.r1c6) AND (t1.r1c7 = t2.r1c7) AND (t1.r1c8 = t2.r1c8) AND
(t1.r1c9 = t2.r1c9) AND (t1.r2c1 = t2.r2c1) AND (t1.r2c2 = t2.r2c2) AND (t1.r2c3 = t2.r2c3) AND
(t1.r2c4 = t2.r2c4) AND (t1.r2c5 = t2.r2c5) AND (t1.r2c6 = t2.r2c6) AND (t1.r2c7 = t2.r2c7) AND
(t1.r2c8 = t2.r2c8) AND (t1.r2c9 = t2.r2c9) AND (t1.r3c1 = t2.r3c1) AND (t1.r3c2 = t2.r3c2) AND
(t1.r3c3 = t2.r3c3) AND (t1.r3c4 = t2.r3c4) AND (t1.r3c5 = t2.r3c5) AND (t1.r3c6 = t2.r3c6) AND
(t1.r3c7 = t2.r3c7) AND (t1.r3c8 = t2.r3c8) AND (t1.r3c9 = t2.r3c9) AND (t1.r4c1 = t2.r4c1) AND
(t1.r4c2 = t2.r4c2) AND (t1.r4c3 = t2.r4c3) AND (t1.r4c4 = t2.r4c4) AND (t1.r4c5 = t2.r4c5) AND
(t1.r4c6 = t2.r4c6) AND (t1.r4c7 = t2.r4c7) AND (t1.r4c8 = t2.r4c8) AND (t1.r4c9 = t2.r4c9) AND
(t1.r5c1 = t2.r5c1) AND (t1.r5c2 = t2.r5c2) AND (t1.r5c3 = t2.r5c3) AND (t1.r5c4 = t2.r5c4) AND
(t1.r5c5 = t2.r5c5) AND (t1.r5c6 = t2.r5c6) AND (t1.r5c7 = t2.r5c7) AND (t1.r5c8 = t2.r5c8) AND
(t1.r5c9 = t2.r5c9) AND (t1.r6c1 = t2.r6c1) AND (t1.r6c2 = t2.r6c2) AND (t1.r6c3 = t2.r6c3) AND
(t1.r6c4 = t2.r6c4) AND (t1.r6c5 = t2.r6c5) AND (t1.r6c6 = t2.r6c6) AND (t1.r6c7 = t2.r6c7) AND
(t1.r6c8 = t2.r6c8) AND (t1.r6c9 = t2.r6c9) AND (t1.r7c1 = t2.r7c1) AND (t1.r7c2 = t2.r7c2) AND
(t1.r7c3 = t2.r7c3) AND (t1.r7c4 = t2.r7c4) AND (t1.r7c5 = t2.r7c5) AND (t1.r7c6 = t2.r7c6) AND
(t1.r7c7 = t2.r7c7) AND (t1.r7c8 = t2.r7c8) AND (t1.r7c9 = t2.r7c9) AND (t1.r8c1 = t2.r8c1) AND
(t1.r8c2 = t2.r8c2) AND (t1.r8c3 = t2.r8c3) AND (t1.r8c4 = t2.r8c4) AND (t1.r8c5 = t2.r8c5) AND
(t1.r8c6 = t2.r8c6) AND (t1.r8c7 = t2.r8c7) AND (t1.r8c8 = t2.r8c8) AND (t1.r8c9 = t2.r8c9) AND
(t1.r9c1 = t2.r9c1) AND (t1.r9c2 = t2.r9c2) AND (t1.r9c3 = t2.r9c3) AND (t1.r9c4 = t2.r9c4) AND
(t1.r9c5 = t2.r9c5) AND (t1.r9c6 = t2.r9c6) AND (t1.r9c7 = t2.r9c7) AND (t1.r9c8 = t2.r9c8) AND
(t1.r9c9 = t2.r9c9);
```

Réessayons l’exemple du début de cet article pour comparer :

```
mysql> SELECT *
-> FROM sudoku_memory_combined_view
-> WHERE
-> (r2c2 = 3) AND (r2c3 = 4) AND (r2c4 = 8) AND (r2c5 = 2) AND
-> (r2c6 = 5) AND (r2c7 = 6) AND (r2c8 = 9) AND (r3c2 = 5) AND
-> (r3c3 = 9) AND (r3c4 = 3) AND (r3c5 = 6) AND (r3c6 = 4) AND
-> (r3c7 = 1) AND (r3c8 = 8) AND (r4c2 = 9) AND (r4c3 = 7) AND
-> (r4c4 = 1) AND (r4c5 = 8) AND (r4c6 = 2) AND (r4c7 = 5) AND
-> (r4c8 = 6) AND (r6c2 = 8) AND (r6c3 = 1) AND (r6c4 = 4) AND
-> (r6c5 = 7) AND (r6c6 = 6) AND (r6c7 = 2) AND (r6c8 = 3) AND
-> (r7c2 = 2) AND (r7c3 = 5) AND (r7c4 = 6) AND (r7c5 = 4) AND
-> (r7c6 = 1) AND (r7c7 = 9) AND (r7c8 = 7) AND (r8c2 = 7) AND
-> (r8c3 = 6) AND (r8c4 = 5) AND (r8c5 = 3) AND (r8c6 = 8) AND
-> (r8c7 = 4) AND (r8c8 = 2);
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
| r1c1 | r1c2 | r1c3 | r1c4 | r1c5 | r1c6 | r1c7 | r1c8 | r1c9 | r2c1 | r2c2 | r2c3 | r2c4 | r2c5 | r2c6 | r2c7 | r2c8 | r2c9 | r3c1 | r3c2 | r3c3 | r3c4 | r3c5 | r3c6 | r3c7 | r3c8 | r3c9 | r4c1 | r4c2 | r4c3 | r4c4 | r4c5 | r4c6 | r4c7 | r4c8 | r4c9 | r5c1 | r5c2 | r5c3 | r5c4 | r5c5 | r5c6 | r5c7 | r5c8 | r5c9 | r6c1 | r6c2 | r6c3 | r6c4 | r6c5 | r6c6 | r6c7 | r6c8 | r6c9 | r7c1 | r7c2 | r7c3 | r7c4 | r7c5 | r7c6 | r7c7 | r7c8 | r7c9 | r8c1 | r8c2 | r8c3 | r8c4 | r8c5 | r8c6 | r8c7 | r8c8 | r8c9 | r9c1 | r9c2 | r9c3 | r9c4 | r9c5 | r9c6 | r9c7 | r9c8 | r9c9 |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
|   2  |   6  |   8  |   7  |   1  |   9  |   3  |   4  |   5  |   1  |   3  |   4  |   8  |   2  |   5  |   6  |   9  |   7  |   7  |   5  |   9  |   3  |   6  |   4  |   1  |   8  |   2  |   3  |   9  |   7  |   1  |   8  |   2  |   5  |   6  |   4  |   6  |   4  |   2  |   9  |   5  |   3  |   7  |   1  |   8  |   5  |   8  |   1  |   4  |   7  |   6  |   2  |   3  |   9  |   8  |   2  |   5  |   6  |   4  |   1  |   9  |   7  |   3  |   9  |   7  |   6  |   5  |   3  |   8  |   4  |   2  |   1  |   4  |   1  |   3  |   2  |   9  |   7  |   8  |   5  |   6  |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
1 row in set (0.55 sec)

```

Wow! Nous sommes passés de 1.5 à 0.55 seconde! Maintenant, qu’en est-il de notre grille à 17 révélés ?

```mysql> SELECT *
-> FROM sudoku_memory_combined_view
-> WHERE
-> (r1c8 = 1) AND
-> (r2c1 = 4) AND
-> (r3c2 = 2) AND
-> (r4c5 = 5) AND
-> (r4c7 = 4) AND
-> (r4c9 = 7) AND
-> (r5c3 = 8) AND
-> (r5c7 = 3) AND
-> (r6c3 = 1) AND
-> (r6c5 = 9) AND
-> (r7c1 = 3) AND
-> (r7c4 = 4) AND
-> (r7c7 = 2) AND
-> (r8c2 = 5) AND
-> (r8c4 = 1) AND
-> (r9c4 = 8) AND
-> (r9c6 = 6);
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
| r1c1 | r1c2 | r1c3 | r1c4 | r1c5 | r1c6 | r1c7 | r1c8 | r1c9 | r2c1 | r2c2 | r2c3 | r2c4 | r2c5 | r2c6 | r2c7 | r2c8 | r2c9 | r3c1 | r3c2 | r3c3 | r3c4 | r3c5 | r3c6 | r3c7 | r3c8 | r3c9 | r4c1 | r4c2 | r4c3 | r4c4 | r4c5 | r4c6 | r4c7 | r4c8 | r4c9 | r5c1 | r5c2 | r5c3 | r5c4 | r5c5 | r5c6 | r5c7 | r5c8 | r5c9 | r6c1 | r6c2 | r6c3 | r6c4 | r6c5 | r6c6 | r6c7 | r6c8 | r6c9 | r7c1 | r7c2 | r7c3 | r7c4 | r7c5 | r7c6 | r7c7 | r7c8 | r7c9 | r8c1 | r8c2 | r8c3 | r8c4 | r8c5 | r8c6 | r8c7 | r8c8 | r8c9 | r9c1 | r9c2 | r9c3 | r9c4 | r9c5 | r9c6 | r9c7 | r9c8 | r9c9 |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
|    6 |    9 |    3 |    7 |    8 |    4 |    5 |    1 |    2 |    4 |    8 |    7 |    5 |    1 |    2 |    9 |    3 |    6 |    1 |    2 |    5 |    9 |    6 |    3 |    8 |    7 |    4 |    9 |    3 |    2 |    6 |    5 |    1 |    4 |    8 |    7 |    5 |    6 |    8 |    2 |    4 |    7 |    3 |    9 |    1 |    7 |    4 |    1 |    3 |    9 |    8 |    6 |    2 |    5 |    3 |    1 |    9 |    4 |    7 |    5 |    2 |    6 |    8 |    8 |    5 |    6 |    1 |    2 |    9 |    7 |    4 |    3 |    2 |    7 |    4 |    8 |    3 |    6 |    1 |    5 |    9 |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
1 row in set (7.41 sec)
```

Fantastique!  Nous sommes passés de 20 minutes à 7 secondes!  Mais il y a encore place à amélioration!

5. Presser encore plus fort

Maintenant que nous sommes en mesure d’obtenir des résultats dans des temps raisonnables en utilisant une table de type MEMORY, nous pouvons regarder du côté des variables système pour essayer de les optimiser.

Mais avant de se lancer dans cette entreprise, il importe d’avoir un jeu d’essai afin d’effectuer des tests reproduisibles et mesurables pour vérifier l’impact de chacun des changements sur ces variables.

Nous allons tout d’abord créer une table qui nous permettra de sauvegarder le temps d’exécution de toutes les grilles de notre jeu d’essai.

```DROP TABLE IF EXISTS tests;

CREATE TABLE tests (
debut DATETIME,
fin DATETIME
) ENGINE=MYISAM;
```

Maintenant, nous allons créer notre jeu d’essai.  Évidemment notre échantillon de grilles est varié de façon à être représentatif afin  de mesurer chaque option de façon précise.

```USE sudoku;
TRUNCATE tests;
INSERT INTO tests(debut, fin) VALUES (NOW(), NULL);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 1) AND (r1c3 = 3) AND (r1c4 = 7) AND (r1c9 = 5) AND (r2c4 = 6) AND (r2c6 = 4) AND (r3c1 = 8) AND (r4c4 = 8) AND (r4c5 = 1) AND (r5c2 = 9) AND (r5c7 = 7) AND (r6c2 = 6) AND (r6c8 = 9) AND (r7c2 = 2) AND (r7c7 = 4) AND (r8c1 = 5) AND (r8c5 = 3) AND (r9c8 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 8) AND (r1c4 = 3) AND (r1c6 = 7) AND (r2c3 = 9) AND (r3c1 = 2) AND (r3c2 = 7) AND (r3c5 = 4) AND (r4c2 = 3) AND (r4c5 = 1) AND (r5c1 = 4) AND (r5c4 = 9) AND (r5c7 = 2) AND (r5c8 = 8) AND (r6c4 = 6) AND (r6c6 = 2) AND (r6c7 = 4) AND (r6c8 = 3) AND (r7c1 = 3) AND (r7c2 = 1) AND (r7c6 = 6) AND (r8c1 = 6) AND (r8c3 = 8) AND (r8c4 = 1) AND (r8c9 = 7) AND (r9c5 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 2) AND (r1c8 = 1) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 3) AND (r3c5 = 5) AND (r4c4 = 4) AND (r4c8 = 6) AND (r5c3 = 2) AND (r5c7 = 9) AND (r6c2 = 5) AND (r6c6 = 8) AND (r7c5 = 3) AND (r7c7 = 5) AND (r8c1 = 7) AND (r8c2 = 9) AND (r8c4 = 1) AND (r9c2 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r2c2 = 8) AND (r3c5 = 5) AND (r3c6 = 3) AND (r3c8 = 8) AND (r3c9 = 9) AND (r4c2 = 2) AND (r4c3 = 4) AND (r4c6 = 9) AND (r5c5 = 1) AND (r5c9 = 5) AND (r6c2 = 1) AND (r6c6 = 7) AND (r7c3 = 2) AND (r7c4 = 1) AND (r7c7 = 3) AND (r8c1 = 9) AND (r8c6 = 5) AND (r8c9 = 7) AND (r9c1 = 5) AND (r9c5 = 8) AND (r9c8 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 5) AND (r1c6 = 8) AND (r1c7 = 6) AND (r2c6 = 6) AND (r2c7 = 2) AND (r2c8 = 7) AND (r3c2 = 1) AND (r4c1 = 9) AND (r4c4 = 7) AND (r4c5 = 6) AND (r4c6 = 2) AND (r5c1 = 7) AND (r6c3 = 8) AND (r7c1 = 2) AND (r7c3 = 3) AND (r7c7 = 8) AND (r8c4 = 1) AND (r8c5 = 9) AND (r8c9 = 5) AND (r9c3 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 5) AND (r1c4 = 8) AND (r1c5 = 3) AND (r2c7 = 7) AND (r2c8 = 1) AND (r3c2 = 3) AND (r4c1 = 7) AND (r4c4 = 4) AND (r4c7 = 8) AND (r5c1 = 1) AND (r5c3 = 2) AND (r7c2 = 8) AND (r7c4 = 6) AND (r7c7 = 4) AND (r8c1 = 9) AND (r8c6 = 2) AND (r9c5 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 7) AND (r1c9 = 5) AND (r2c2 = 3) AND (r2c8 = 7) AND (r3c1 = 2) AND (r3c3 = 5) AND (r3c8 = 3) AND (r3c9 = 8) AND (r4c8 = 8) AND (r4c9 = 9) AND (r5c1 = 5) AND (r5c3 = 8) AND (r5c4 = 2) AND (r5c6 = 9) AND (r5c7 = 7) AND (r5c9 = 4) AND (r6c1 = 3) AND (r7c1 = 6) AND (r7c3 = 4) AND (r7c4 = 9) AND (r7c5 = 8) AND (r7c6 = 7) AND (r7c7 = 5) AND (r8c1 = 9) AND (r8c4 = 5) AND (r9c4 = 4) AND (r9c6 = 6) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c2 = 6) AND (r1c3 = 8) AND (r1c7 = 1) AND (r2c2 = 7) AND (r2c4 = 4) AND (r2c6 = 8) AND (r2c8 = 5) AND (r3c4 = 6) AND (r4c3 = 6) AND (r4c4 = 1) AND (r4c5 = 8) AND (r4c6 = 3) AND (r4c9 = 7) AND (r5c3 = 7) AND (r6c1 = 3) AND (r6c5 = 5) AND (r6c7 = 2) AND (r6c9 = 1) AND (r7c6 = 7) AND (r8c4 = 8) AND (r8c6 = 2) AND (r8c7 = 5) AND (r9c6 = 5) AND (r9c7 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c8 = 1) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 5) AND (r3c5 = 6) AND (r4c4 = 3) AND (r4c8 = 7) AND (r5c3 = 2) AND (r5c7 = 6) AND (r6c2 = 1) AND (r6c6 = 5) AND (r7c5 = 8) AND (r7c7 = 2) AND (r8c1 = 7) AND (r8c2 = 3) AND (r8c4 = 9) AND (r9c2 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 7) AND (r1c9 = 2) AND (r2c5 = 4) AND (r2c6 = 5) AND (r2c8 = 7) AND (r3c3 = 9) AND (r4c1 = 3) AND (r4c5 = 5) AND (r4c7 = 8) AND (r5c1 = 4) AND (r5c2 = 8) AND (r5c4 = 9) AND (r5c6 = 1) AND (r5c9 = 7) AND (r6c3 = 7) AND (r6c6 = 4) AND (r6c7 = 2) AND (r6c9 = 9) AND (r7c5 = 1) AND (r7c7 = 3) AND (r8c8 = 5) AND (r9c2 = 3) AND (r9c4 = 8) AND (r9c5 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 9) AND (r1c8 = 7) AND (r2c8 = 2) AND (r2c9 = 4) AND (r3c1 = 1) AND (r4c2 = 2) AND (r4c3 = 9) AND (r4c9 = 5) AND (r5c6 = 1) AND (r5c7 = 6) AND (r6c2 = 4) AND (r6c5 = 8) AND (r7c4 = 4) AND (r7c5 = 3) AND (r8c1 = 5) AND (r8c7 = 8) AND (r9c4 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r2c2 = 9) AND (r2c3 = 3) AND (r3c2 = 7) AND (r3c8 = 3) AND (r4c3 = 9) AND (r4c5 = 6) AND (r4c8 = 7) AND (r4c9 = 4) AND (r5c3 = 6) AND (r5c5 = 7) AND (r5c7 = 3) AND (r5c8 = 9) AND (r6c2 = 3) AND (r6c4 = 5) AND (r6c7 = 6) AND (r6c8 = 8) AND (r7c1 = 9) AND (r7c5 = 8) AND (r7c6 = 2) AND (r7c7 = 4) AND (r8c2 = 8) AND (r8c3 = 2) AND (r8c5 = 3) AND (r8c8 = 5) AND (r8c9 = 7) AND (r9c2 = 6) AND (r9c3 = 4) AND (r9c4 = 7) AND (r9c5 = 5) AND (r9c8 = 2) AND (r9c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c5 = 5) AND (r1c8 = 6) AND (r1c9 = 9) AND (r2c1 = 6) AND (r2c8 = 4) AND (r3c2 = 1) AND (r3c5 = 8) AND (r3c6 = 9) AND (r3c9 = 3) AND (r4c4 = 1) AND (r5c4 = 3) AND (r6c2 = 8) AND (r6c8 = 9) AND (r7c1 = 4) AND (r7c2 = 6) AND (r8c3 = 7) AND (r8c6 = 3) AND (r8c9 = 8) AND (r9c2 = 5) AND (r9c3 = 8) AND (r9c4 = 7) AND (r9c6 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 7) AND (r1c5 = 9) AND (r1c6 = 4) AND (r2c2 = 1) AND (r2c6 = 7) AND (r3c3 = 9) AND (r3c4 = 2) AND (r3c5 = 1) AND (r4c1 = 2) AND (r4c4 = 5) AND (r4c6 = 9) AND (r5c3 = 8) AND (r5c4 = 6) AND (r6c1 = 9) AND (r6c2 = 5) AND (r6c6 = 1) AND (r6c8 = 2) AND (r6c9 = 7) AND (r7c1 = 8) AND (r7c6 = 2) AND (r7c7 = 6) AND (r8c1 = 1) AND (r8c5 = 5) AND (r8c6 = 8) AND (r8c9 = 2) AND (r9c4 = 7) AND (r9c5 = 4) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 1) AND (r1c4 = 6) AND (r1c5 = 2) AND (r2c1 = 5) AND (r2c8 = 4) AND (r2c9 = 3) AND (r3c5 = 9) AND (r4c1 = 7) AND (r4c8 = 8) AND (r5c3 = 5) AND (r5c9 = 4) AND (r6c4 = 1) AND (r7c6 = 3) AND (r7c7 = 6) AND (r8c2 = 9) AND (r8c7 = 2) AND (r9c1 = 8) AND (r9c6 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 5) AND (r1c3 = 8) AND (r1c6 = 6) AND (r1c7 = 3) AND (r1c8 = 2) AND (r1c9 = 4) AND (r2c1 = 9) AND (r2c2 = 2) AND (r2c3 = 3) AND (r2c6 = 8) AND (r2c7 = 5) AND (r2c8 = 6) AND (r3c5 = 5) AND (r4c9 = 8) AND (r5c2 = 8) AND (r5c3 = 7) AND (r5c6 = 9) AND (r7c2 = 4) AND (r7c4 = 6) AND (r7c6 = 7) AND (r7c8 = 5) AND (r8c1 = 3) AND (r8c5 = 9) AND (r8c6 = 5) AND (r8c8 = 8) AND (r8c9 = 2) AND (r9c2 = 9) AND (r9c3 = 5) AND (r9c5 = 8) AND (r9c7 = 6) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 3) AND (r1c5 = 7) AND (r1c7 = 8) AND (r2c4 = 4) AND (r2c6 = 3) AND (r3c1 = 2) AND (r3c4 = 5) AND (r3c5 = 6) AND (r3c6 = 8) AND (r3c9 = 3) AND (r4c2 = 6) AND (r4c3 = 2) AND (r4c7 = 5) AND (r4c8 = 3) AND (r5c1 = 1) AND (r5c3 = 5) AND (r5c7 = 9) AND (r5c9 = 4) AND (r6c2 = 3) AND (r6c3 = 9) AND (r6c7 = 2) AND (r6c8 = 1) AND (r7c1 = 3) AND (r7c4 = 6) AND (r7c5 = 2) AND (r7c6 = 7) AND (r7c9 = 5) AND (r8c4 = 9) AND (r8c6 = 5) AND (r9c3 = 7) AND (r9c5 = 8) AND (r9c7 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 3) AND (r1c3 = 8) AND (r2c1 = 7) AND (r2c6 = 8) AND (r3c1 = 6) AND (r3c2 = 4) AND (r3c3 = 9) AND (r3c4 = 3) AND (r3c5 = 1) AND (r3c6 = 7) AND (r3c8 = 2) AND (r4c1 = 1) AND (r4c2 = 7) AND (r4c5 = 3) AND (r4c6 = 6) AND (r4c8 = 8) AND (r4c9 = 2) AND (r5c1 = 3) AND (r5c3 = 6) AND (r5c4 = 2) AND (r5c6 = 1) AND (r5c8 = 7) AND (r5c9 = 9) AND (r6c5 = 7) AND (r7c1 = 4) AND (r7c2 = 9) AND (r7c8 = 1) AND (r8c2 = 6) AND (r8c3 = 1) AND (r8c5 = 9) AND (r8c8 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 5) AND (r1c8 = 8) AND (r2c2 = 1) AND (r2c6 = 3) AND (r3c1 = 3) AND (r3c3 = 7) AND (r3c4 = 6) AND (r4c2 = 9) AND (r4c4 = 1) AND (r4c5 = 7) AND (r4c6 = 6) AND (r4c7 = 3) AND (r5c4 = 9) AND (r5c6 = 8) AND (r5c8 = 1) AND (r6c1 = 2) AND (r7c2 = 6) AND (r8c2 = 8) AND (r8c6 = 1) AND (r8c8 = 6) AND (r9c2 = 3) AND (r9c4 = 2) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 8) AND (r1c7 = 4) AND (r1c9 = 3) AND (r2c1 = 9) AND (r2c4 = 3) AND (r2c7 = 7) AND (r3c2 = 1) AND (r3c3 = 5) AND (r3c6 = 2) AND (r4c1 = 6) AND (r4c8 = 9) AND (r4c9 = 5) AND (r5c2 = 3) AND (r5c3 = 7) AND (r6c4 = 8) AND (r7c7 = 8) AND (r7c8 = 3) AND (r7c9 = 2) AND (r8c2 = 2) AND (r8c5 = 9) AND (r9c1 = 8) AND (r9c4 = 7) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 7) AND (r1c4 = 2) AND (r1c6 = 4) AND (r1c8 = 5) AND (r2c2 = 4) AND (r2c9 = 2) AND (r3c2 = 2) AND (r3c5 = 8) AND (r3c9 = 6) AND (r4c3 = 7) AND (r4c9 = 5) AND (r5c1 = 8) AND (r5c4 = 5) AND (r6c1 = 6) AND (r6c3 = 3) AND (r6c8 = 7) AND (r7c3 = 9) AND (r7c4 = 7) AND (r8c1 = 3) AND (r8c3 = 2) AND (r8c5 = 5) AND (r8c8 = 6) AND (r9c3 = 5) AND (r9c4 = 3) AND (r9c7 = 9) AND (r9c8 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 8) AND (r1c8 = 7) AND (r2c1 = 2) AND (r2c2 = 6) AND (r3c2 = 4) AND (r3c5 = 6) AND (r3c6 = 5) AND (r4c3 = 7) AND (r5c6 = 2) AND (r5c8 = 3) AND (r6c6 = 3) AND (r6c8 = 4) AND (r6c9 = 5) AND (r7c4 = 3) AND (r8c3 = 2) AND (r8c4 = 8) AND (r8c5 = 9) AND (r8c6 = 7) AND (r9c2 = 5) AND (r9c9 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 3) AND (r1c5 = 8) AND (r1c8 = 7) AND (r1c9 = 1) AND (r2c2 = 6) AND (r2c3 = 7) AND (r3c1 = 8) AND (r5c1 = 7) AND (r5c2 = 2) AND (r5c3 = 9) AND (r5c5 = 3) AND (r5c6 = 1) AND (r5c8 = 6) AND (r5c9 = 4) AND (r6c1 = 3) AND (r6c2 = 8) AND (r6c3 = 1) AND (r7c3 = 8) AND (r7c5 = 1) AND (r7c7 = 7) AND (r7c8 = 4) AND (r8c2 = 1) AND (r8c3 = 2) AND (r8c4 = 6) AND (r8c8 = 8) AND (r8c9 = 3) AND (r9c1 = 6) AND (r9c4 = 3) AND (r9c5 = 4) AND (r9c8 = 1) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c8 = 4) AND (r2c5 = 8) AND (r2c9 = 7) AND (r3c4 = 1) AND (r3c5 = 4) AND (r3c6 = 6) AND (r3c7 = 9) AND (r3c9 = 8) AND (r4c1 = 2) AND (r4c5 = 6) AND (r4c9 = 3) AND (r5c3 = 1) AND (r5c5 = 9) AND (r5c9 = 6) AND (r6c2 = 8) AND (r6c3 = 6) AND (r6c4 = 3) AND (r6c5 = 7) AND (r6c7 = 4) AND (r7c5 = 1) AND (r7c7 = 7) AND (r8c1 = 9) AND (r8c2 = 4) AND (r8c8 = 3) AND (r8c9 = 1) AND (r9c6 = 7) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 3) AND (r1c5 = 2) AND (r1c6 = 6) AND (r2c7 = 4) AND (r2c9 = 1) AND (r3c1 = 5) AND (r4c1 = 2) AND (r4c8 = 6) AND (r5c6 = 5) AND (r5c8 = 3) AND (r6c2 = 4) AND (r6c4 = 1) AND (r7c4 = 4) AND (r7c5 = 1) AND (r7c7 = 7) AND (r8c4 = 8) AND (r9c1 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 4) AND (r1c7 = 8) AND (r1c8 = 1) AND (r2c1 = 9) AND (r2c4 = 6) AND (r2c6 = 7) AND (r3c3 = 8) AND (r3c6 = 2) AND (r3c8 = 6) AND (r4c6 = 1) AND (r4c8 = 4) AND (r4c9 = 2) AND (r5c2 = 3) AND (r6c1 = 6) AND (r6c2 = 4) AND (r7c1 = 8) AND (r7c2 = 1) AND (r8c7 = 4) AND (r8c8 = 3) AND (r9c3 = 7) AND (r9c4 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 3) AND (r1c3 = 4) AND (r1c6 = 5) AND (r1c8 = 8) AND (r2c2 = 5) AND (r2c5 = 9) AND (r2c8 = 4) AND (r2c9 = 3) AND (r3c1 = 9) AND (r3c2 = 8) AND (r3c4 = 2) AND (r3c9 = 5) AND (r4c1 = 3) AND (r4c5 = 7) AND (r4c9 = 8) AND (r5c2 = 4) AND (r5c6 = 3) AND (r5c7 = 6) AND (r5c8 = 9) AND (r6c2 = 9) AND (r6c5 = 6) AND (r6c7 = 2) AND (r7c1 = 6) AND (r7c5 = 5) AND (r7c6 = 7) AND (r8c5 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 2) AND (r1c5 = 5) AND (r1c6 = 4) AND (r1c7 = 3) AND (r1c8 = 6) AND (r1c9 = 1) AND (r2c4 = 2) AND (r3c5 = 1) AND (r3c6 = 9) AND (r4c4 = 4) AND (r4c6 = 8) AND (r5c2 = 4) AND (r5c4 = 3) AND (r5c5 = 2) AND (r5c6 = 5) AND (r5c7 = 1) AND (r5c8 = 8) AND (r6c5 = 6) AND (r6c8 = 9) AND (r6c9 = 4) AND (r7c1 = 3) AND (r7c4 = 1) AND (r7c6 = 2) AND (r7c9 = 5) AND (r8c9 = 3) AND (r9c6 = 6) AND (r9c7 = 2) AND (r9c8 = 1) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 1) AND (r1c5 = 6) AND (r2c2 = 3) AND (r2c7 = 5) AND (r2c9 = 4) AND (r3c5 = 2) AND (r4c8 = 7) AND (r4c9 = 2) AND (r5c3 = 1) AND (r5c4 = 5) AND (r5c5 = 7) AND (r5c7 = 9) AND (r6c2 = 4) AND (r6c8 = 1) AND (r7c2 = 9) AND (r7c3 = 2) AND (r8c4 = 7) AND (r8c7 = 6) AND (r8c8 = 3) AND (r9c8 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c3 = 5) AND (r1c9 = 2) AND (r2c4 = 9) AND (r2c6 = 1) AND (r3c1 = 3) AND (r4c2 = 6) AND (r4c4 = 7) AND (r4c7 = 4) AND (r5c1 = 2) AND (r5c5 = 5) AND (r6c8 = 6) AND (r7c4 = 3) AND (r7c5 = 8) AND (r8c2 = 1) AND (r8c7 = 7) AND (r9c2 = 4) AND (r9c8 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r2c2 = 7) AND (r2c7 = 8) AND (r2c9 = 4) AND (r3c5 = 9) AND (r3c6 = 8) AND (r3c7 = 3) AND (r3c9 = 2) AND (r4c1 = 6) AND (r4c4 = 1) AND (r4c7 = 9) AND (r5c3 = 7) AND (r5c8 = 3) AND (r6c1 = 2) AND (r6c2 = 8) AND (r6c6 = 3) AND (r6c7 = 6) AND (r7c2 = 3) AND (r7c4 = 9) AND (r7c5 = 4) AND (r7c6 = 6) AND (r7c9 = 8) AND (r8c2 = 2) AND (r9c1 = 1) AND (r9c3 = 4) AND (r9c4 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 6) AND (r1c8 = 1) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 2) AND (r3c5 = 5) AND (r4c4 = 6) AND (r4c8 = 7) AND (r5c3 = 8) AND (r5c7 = 9) AND (r6c2 = 5) AND (r6c6 = 3) AND (r7c5 = 6) AND (r7c7 = 5) AND (r8c1 = 7) AND (r8c2 = 1) AND (r8c4 = 9) AND (r9c2 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c3 = 3) AND (r1c7 = 6) AND (r1c8 = 4) AND (r2c1 = 1) AND (r2c2 = 2) AND (r2c5 = 6) AND (r2c7 = 5) AND (r3c1 = 5) AND (r3c4 = 8) AND (r3c5 = 9) AND (r3c6 = 3) AND (r3c8 = 2) AND (r3c9 = 1) AND (r4c5 = 3) AND (r5c2 = 6) AND (r5c5 = 2) AND (r5c6 = 5) AND (r5c8 = 1) AND (r5c9 = 3) AND (r6c2 = 1) AND (r6c6 = 9) AND (r6c8 = 5) AND (r7c1 = 4) AND (r7c4 = 3) AND (r7c6 = 1) AND (r8c2 = 5) AND (r9c4 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 5) AND (r1c3 = 3) AND (r1c5 = 9) AND (r2c7 = 8) AND (r2c9 = 1) AND (r3c1 = 2) AND (r4c1 = 4) AND (r4c5 = 2) AND (r4c8 = 5) AND (r5c2 = 1) AND (r5c4 = 8) AND (r6c2 = 6) AND (r6c4 = 7) AND (r7c4 = 4) AND (r7c6 = 7) AND (r7c7 = 6) AND (r8c8 = 3) AND (r9c1 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 1) AND (r1c4 = 7) AND (r1c7 = 2) AND (r1c9 = 5) AND (r2c8 = 6) AND (r2c9 = 3) AND (r3c3 = 3) AND (r3c5 = 6) AND (r4c1 = 5) AND (r4c4 = 3) AND (r4c9 = 7) AND (r6c3 = 8) AND (r6c4 = 2) AND (r6c6 = 7) AND (r6c7 = 3) AND (r6c8 = 9) AND (r7c8 = 7) AND (r8c1 = 2) AND (r8c4 = 5) AND (r8c7 = 1) AND (r9c2 = 6) AND (r9c4 = 8) AND (r9c5 = 3) AND (r9c6 = 1) AND (r9c7 = 5) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 9) AND (r1c4 = 5) AND (r1c6 = 6) AND (r1c7 = 4) AND (r1c8 = 2) AND (r2c1 = 2) AND (r2c2 = 3) AND (r2c7 = 8) AND (r2c9 = 5) AND (r3c2 = 5) AND (r3c3 = 4) AND (r3c5 = 3) AND (r3c8 = 6) AND (r3c9 = 9) AND (r4c3 = 8) AND (r4c4 = 6) AND (r4c5 = 7) AND (r4c6 = 5) AND (r6c4 = 3) AND (r6c5 = 2) AND (r6c6 = 9) AND (r6c9 = 6) AND (r7c2 = 4) AND (r7c3 = 2) AND (r7c5 = 9) AND (r7c6 = 3) AND (r7c7 = 6) AND (r8c4 = 4) AND (r8c5 = 6) AND (r9c1 = 3) AND (r9c4 = 2) AND (r9c6 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 3) AND (r1c5 = 5) AND (r2c3 = 9) AND (r2c7 = 1) AND (r3c6 = 9) AND (r3c9 = 6) AND (r4c4 = 8) AND (r4c9 = 5) AND (r5c5 = 1) AND (r5c7 = 8) AND (r5c8 = 3) AND (r6c2 = 3) AND (r6c3 = 2) AND (r6c8 = 7) AND (r7c1 = 1) AND (r7c2 = 8) AND (r7c7 = 3) AND (r8c3 = 7) AND (r8c8 = 2) AND (r9c2 = 5) AND (r9c7 = 7) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 6) AND (r1c7 = 8) AND (r1c9 = 7) AND (r2c3 = 3) AND (r2c8 = 4) AND (r3c1 = 2) AND (r3c2 = 9) AND (r3c5 = 7) AND (r3c9 = 6) AND (r4c4 = 9) AND (r4c7 = 2) AND (r4c9 = 3) AND (r5c4 = 2) AND (r5c5 = 6) AND (r5c9 = 9) AND (r7c1 = 3) AND (r7c2 = 8) AND (r7c5 = 2) AND (r8c3 = 7) AND (r8c7 = 1) AND (r8c9 = 4) AND (r9c4 = 1) AND (r9c8 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c8 = 1) AND (r2c6 = 1) AND (r2c8 = 2) AND (r2c9 = 3) AND (r3c5 = 5) AND (r4c4 = 6) AND (r4c8 = 4) AND (r5c3 = 3) AND (r5c7 = 5) AND (r6c2 = 7) AND (r6c6 = 2) AND (r7c5 = 4) AND (r7c7 = 8) AND (r8c1 = 2) AND (r8c2 = 1) AND (r8c4 = 8) AND (r8c8 = 7) AND (r9c2 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 5) AND (r1c5 = 7) AND (r1c7 = 4) AND (r1c8 = 1) AND (r2c3 = 7) AND (r2c4 = 2) AND (r2c7 = 3) AND (r2c9 = 9) AND (r3c5 = 4) AND (r3c7 = 7) AND (r3c9 = 2) AND (r4c3 = 8) AND (r4c6 = 2) AND (r5c4 = 3) AND (r5c5 = 9) AND (r5c7 = 2) AND (r5c8 = 4) AND (r6c2 = 3) AND (r6c4 = 4) AND (r6c9 = 5) AND (r7c4 = 9) AND (r7c5 = 2) AND (r7c7 = 5) AND (r8c4 = 8) AND (r8c5 = 1) AND (r8c6 = 4) AND (r8c9 = 7) AND (r9c1 = 8) AND (r9c6 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r2c2 = 7) AND (r2c4 = 6) AND (r2c5 = 3) AND (r3c3 = 9) AND (r3c4 = 8) AND (r3c8 = 6) AND (r4c7 = 7) AND (r4c8 = 3) AND (r5c3 = 2) AND (r5c4 = 3) AND (r5c7 = 5) AND (r5c9 = 9) AND (r6c3 = 6) AND (r6c5 = 1) AND (r6c7 = 2) AND (r7c1 = 2) AND (r7c3 = 3) AND (r7c6 = 1) AND (r8c1 = 9) AND (r8c5 = 6) AND (r8c9 = 8) AND (r9c2 = 8) AND (r9c3 = 1) AND (r9c4 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 9) AND (r2c4 = 3) AND (r2c5 = 6) AND (r2c7 = 1) AND (r3c5 = 1) AND (r3c6 = 9) AND (r3c7 = 5) AND (r4c1 = 5) AND (r4c8 = 9) AND (r4c9 = 2) AND (r5c5 = 7) AND (r6c4 = 6) AND (r6c9 = 3) AND (r7c4 = 9) AND (r7c7 = 7) AND (r7c8 = 5) AND (r8c5 = 5) AND (r8c6 = 1) AND (r8c8 = 2) AND (r9c2 = 6) AND (r9c5 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 3) AND (r1c3 = 7) AND (r2c1 = 9) AND (r2c2 = 4) AND (r2c3 = 6) AND (r2c9 = 3) AND (r3c1 = 1) AND (r3c4 = 7) AND (r4c1 = 2) AND (r4c2 = 8) AND (r4c3 = 1) AND (r4c4 = 4) AND (r5c3 = 3) AND (r5c6 = 6) AND (r6c1 = 4) AND (r7c5 = 1) AND (r7c7 = 9) AND (r7c9 = 2) AND (r8c3 = 2) AND (r8c4 = 9) AND (r8c6 = 4) AND (r8c9 = 6) AND (r9c1 = 3) AND (r9c2 = 1) AND (r9c5 = 8) AND (r9c8 = 4) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r2c1 = 4) AND (r2c2 = 2) AND (r2c3 = 9) AND (r2c5 = 8) AND (r2c6 = 3) AND (r3c2 = 8) AND (r3c4 = 5) AND (r3c6 = 4) AND (r4c5 = 2) AND (r4c7 = 4) AND (r4c8 = 7) AND (r5c2 = 4) AND (r5c4 = 8) AND (r5c6 = 9) AND (r5c8 = 5) AND (r6c3 = 2) AND (r6c4 = 1) AND (r6c7 = 3) AND (r6c9 = 8) AND (r7c2 = 9) AND (r8c1 = 8) AND (r8c5 = 7) AND (r8c6 = 2) AND (r8c9 = 4) AND (r9c4 = 9) AND (r9c5 = 1) AND (r9c6 = 8) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 2) AND (r1c7 = 4) AND (r1c9 = 9) AND (r2c2 = 4) AND (r2c8 = 5) AND (r2c9 = 2) AND (r3c3 = 5) AND (r3c7 = 8) AND (r3c8 = 7) AND (r4c2 = 8) AND (r4c8 = 9) AND (r4c9 = 6) AND (r5c3 = 7) AND (r5c6 = 9) AND (r5c7 = 2) AND (r5c8 = 3) AND (r6c3 = 2) AND (r6c5 = 3) AND (r6c7 = 7) AND (r6c9 = 8) AND (r7c2 = 5) AND (r7c5 = 8) AND (r7c7 = 9) AND (r8c1 = 2) AND (r8c3 = 6) AND (r9c3 = 8) AND (r9c4 = 5) AND (r9c6 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c5 = 6) AND (r2c3 = 2) AND (r2c7 = 6) AND (r3c2 = 1) AND (r3c6 = 9) AND (r3c7 = 5) AND (r3c9 = 3) AND (r4c2 = 7) AND (r4c7 = 8) AND (r5c1 = 1) AND (r5c8 = 3) AND (r6c3 = 9) AND (r6c9 = 5) AND (r7c2 = 8) AND (r7c6 = 3) AND (r7c9 = 9) AND (r8c1 = 7) AND (r8c3 = 5) AND (r8c6 = 2) AND (r8c7 = 1) AND (r8c9 = 6) AND (r9c1 = 6) AND (r9c8 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 3) AND (r1c8 = 1) AND (r2c1 = 7) AND (r2c4 = 5) AND (r3c1 = 2) AND (r3c5 = 4) AND (r4c2 = 3) AND (r4c3 = 9) AND (r4c6 = 8) AND (r5c8 = 6) AND (r5c9 = 2) AND (r6c2 = 1) AND (r7c1 = 5) AND (r7c4 = 6) AND (r7c9 = 7) AND (r8c2 = 8) AND (r8c7 = 9) AND (r9c5 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 5) AND (r1c3 = 1) AND (r1c5 = 7) AND (r1c8 = 6) AND (r1c9 = 3) AND (r2c2 = 6) AND (r2c8 = 2) AND (r3c2 = 2) AND (r3c3 = 3) AND (r3c5 = 6) AND (r3c7 = 7) AND (r3c8 = 9) AND (r5c2 = 1) AND (r5c7 = 3) AND (r5c8 = 5) AND (r6c3 = 9) AND (r6c8 = 4) AND (r7c1 = 6) AND (r7c4 = 4) AND (r7c6 = 9) AND (r7c7 = 5) AND (r8c1 = 5) AND (r8c2 = 9) AND (r8c4 = 6) AND (r8c5 = 3) AND (r8c8 = 7) AND (r8c9 = 4) AND (r9c3 = 4) AND (r9c4 = 7) AND (r9c5 = 5) AND (r9c8 = 3) AND (r9c9 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 7) AND (r1c8 = 9) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 2) AND (r3c5 = 5) AND (r4c4 = 4) AND (r4c8 = 2) AND (r5c3 = 6) AND (r5c7 = 7) AND (r6c2 = 5) AND (r6c6 = 3) AND (r7c5 = 6) AND (r7c7 = 5) AND (r8c1 = 8) AND (r8c2 = 1) AND (r8c4 = 9) AND (r9c2 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 1) AND (r1c8 = 8) AND (r2c6 = 1) AND (r2c8 = 2) AND (r2c9 = 3) AND (r3c3 = 4) AND (r3c5 = 5) AND (r4c4 = 2) AND (r4c8 = 6) AND (r5c3 = 7) AND (r5c7 = 8) AND (r6c2 = 5) AND (r6c6 = 9) AND (r7c5 = 7) AND (r7c7 = 5) AND (r8c1 = 6) AND (r8c2 = 3) AND (r8c4 = 8) AND (r9c2 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 2) AND (r1c3 = 7) AND (r1c5 = 3) AND (r1c6 = 4) AND (r1c8 = 6) AND (r1c9 = 5) AND (r2c6 = 8) AND (r2c9 = 2) AND (r3c3 = 4) AND (r3c7 = 7) AND (r4c1 = 4) AND (r4c9 = 3) AND (r5c1 = 8) AND (r5c3 = 2) AND (r5c7 = 6) AND (r5c8 = 4) AND (r6c2 = 7) AND (r6c9 = 8) AND (r7c2 = 2) AND (r7c3 = 1) AND (r7c5 = 8) AND (r7c8 = 5) AND (r8c1 = 6) AND (r8c2 = 4) AND (r8c5 = 2) AND (r8c6 = 5) AND (r8c7 = 3) AND (r9c1 = 5) AND (r9c6 = 7) AND (r9c9 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c8 = 8) AND (r2c1 = 3) AND (r2c4 = 5) AND (r2c6 = 7) AND (r2c7 = 1) AND (r3c6 = 1) AND (r3c8 = 6) AND (r3c9 = 3) AND (r4c3 = 2) AND (r5c1 = 8) AND (r5c3 = 7) AND (r5c7 = 2) AND (r5c8 = 3) AND (r6c1 = 5) AND (r6c5 = 7) AND (r7c2 = 8) AND (r7c5 = 4) AND (r7c6 = 3) AND (r7c8 = 2) AND (r7c9 = 1) AND (r8c1 = 1) AND (r8c3 = 5) AND (r8c9 = 6) AND (r9c1 = 4) AND (r9c2 = 3) AND (r9c7 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 3) AND (r1c8 = 1) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 5) AND (r3c5 = 7) AND (r4c4 = 4) AND (r4c8 = 5) AND (r5c3 = 7) AND (r5c7 = 6) AND (r6c2 = 8) AND (r6c6 = 1) AND (r7c5 = 5) AND (r7c7 = 8) AND (r8c1 = 1) AND (r8c2 = 2) AND (r8c4 = 3) AND (r9c2 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c5 = 3) AND (r1c6 = 1) AND (r2c1 = 3) AND (r2c4 = 4) AND (r2c5 = 2) AND (r2c8 = 6) AND (r3c4 = 6) AND (r3c6 = 9) AND (r4c5 = 7) AND (r4c6 = 3) AND (r4c7 = 4) AND (r5c2 = 7) AND (r5c4 = 1) AND (r5c6 = 2) AND (r5c7 = 5) AND (r5c8 = 3) AND (r6c4 = 5) AND (r6c5 = 4) AND (r6c8 = 1) AND (r7c2 = 1) AND (r7c7 = 3) AND (r8c1 = 5) AND (r8c2 = 3) AND (r8c7 = 6) AND (r8c8 = 9) AND (r9c2 = 6) AND (r9c3 = 9) AND (r9c5 = 1) AND (r9c6 = 4) AND (r9c7 = 2) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 8) AND (r1c7 = 4) AND (r2c2 = 2) AND (r2c6 = 1) AND (r2c8 = 9) AND (r3c5 = 7) AND (r3c9 = 5) AND (r4c4 = 4) AND (r4c7 = 8) AND (r5c5 = 5) AND (r5c9 = 7) AND (r6c1 = 1) AND (r6c6 = 9) AND (r6c8 = 2) AND (r7c1 = 9) AND (r7c6 = 6) AND (r7c7 = 1) AND (r7c8 = 3) AND (r8c1 = 2) AND (r9c1 = 6) AND (r9c3 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 3) AND (r1c3 = 4) AND (r1c4 = 6) AND (r1c7 = 9) AND (r1c8 = 2) AND (r1c9 = 1) AND (r2c1 = 2) AND (r3c2 = 1) AND (r3c3 = 9) AND (r3c9 = 5) AND (r4c2 = 4) AND (r4c3 = 2) AND (r4c9 = 9) AND (r5c2 = 9) AND (r5c3 = 6) AND (r6c1 = 3) AND (r6c4 = 9) AND (r6c8 = 6) AND (r7c2 = 2) AND (r7c3 = 1) AND (r7c5 = 4) AND (r7c6 = 9) AND (r7c8 = 5) AND (r8c4 = 5) AND (r8c6 = 6) AND (r8c8 = 1) AND (r9c4 = 2) AND (r9c5 = 1) AND (r9c7 = 7) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c9 = 4) AND (r2c2 = 3) AND (r2c3 = 1) AND (r2c6 = 9) AND (r2c9 = 7) AND (r3c1 = 2) AND (r3c2 = 9) AND (r3c6 = 1) AND (r4c2 = 7) AND (r4c6 = 6) AND (r5c6 = 2) AND (r5c9 = 9) AND (r6c4 = 7) AND (r6c5 = 4) AND (r7c1 = 5) AND (r7c5 = 1) AND (r7c8 = 2) AND (r8c2 = 6) AND (r8c5 = 9) AND (r8c8 = 7) AND (r8c9 = 3) AND (r9c3 = 3) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 4) AND (r1c6 = 2) AND (r1c7 = 5) AND (r1c8 = 6) AND (r2c4 = 7) AND (r2c9 = 3) AND (r3c2 = 1) AND (r4c1 = 6) AND (r4c5 = 9) AND (r4c6 = 8) AND (r5c5 = 1) AND (r6c9 = 4) AND (r7c7 = 1) AND (r7c8 = 8) AND (r8c1 = 4) AND (r8c4 = 3) AND (r9c1 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c4 = 4) AND (r1c5 = 2) AND (r1c6 = 6) AND (r1c7 = 1) AND (r2c2 = 4) AND (r2c4 = 3) AND (r2c5 = 7) AND (r2c8 = 2) AND (r3c3 = 6) AND (r3c5 = 1) AND (r3c6 = 5) AND (r3c8 = 7) AND (r4c1 = 6) AND (r5c2 = 8) AND (r5c4 = 5) AND (r6c1 = 4) AND (r6c2 = 5) AND (r6c3 = 2) AND (r6c5 = 6) AND (r6c6 = 3) AND (r7c1 = 5) AND (r7c4 = 7) AND (r7c9 = 2) AND (r8c1 = 7) AND (r8c9 = 1) AND (r9c1 = 3) AND (r9c3 = 4) AND (r9c4 = 6) AND (r9c5 = 5) AND (r9c6 = 2) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 9) AND (r1c7 = 3) AND (r1c9 = 6) AND (r2c1 = 7) AND (r2c4 = 6) AND (r2c6 = 4) AND (r2c7 = 8) AND (r3c1 = 6) AND (r3c2 = 1) AND (r3c5 = 3) AND (r3c9 = 7) AND (r4c1 = 1) AND (r4c2 = 6) AND (r4c7 = 4) AND (r4c9 = 3) AND (r5c6 = 1) AND (r5c7 = 7) AND (r6c2 = 8) AND (r6c4 = 4) AND (r6c5 = 9) AND (r6c8 = 1) AND (r7c2 = 9) AND (r7c5 = 4) AND (r8c9 = 4) AND (r9c1 = 2) AND (r9c2 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c2 = 3) AND (r1c5 = 7) AND (r1c6 = 6) AND (r1c7 = 5) AND (r1c8 = 9) AND (r2c2 = 6) AND (r2c3 = 5) AND (r2c5 = 4) AND (r3c4 = 5) AND (r3c5 = 9) AND (r3c7 = 3) AND (r4c2 = 1) AND (r4c6 = 8) AND (r4c7 = 4) AND (r4c8 = 5) AND (r5c1 = 3) AND (r5c2 = 7) AND (r5c4 = 6) AND (r5c6 = 4) AND (r5c7 = 1) AND (r5c9 = 9) AND (r6c5 = 1) AND (r6c6 = 9) AND (r6c8 = 7) AND (r6c9 = 3) AND (r7c2 = 9) AND (r7c5 = 8) AND (r8c2 = 5) AND (r8c5 = 6) AND (r8c6 = 7) AND (r8c7 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c2 = 4) AND (r1c6 = 6) AND (r1c8 = 2) AND (r2c3 = 6) AND (r2c9 = 9) AND (r3c7 = 1) AND (r4c5 = 9) AND (r4c8 = 3) AND (r5c1 = 3) AND (r5c2 = 6) AND (r5c7 = 9) AND (r6c3 = 2) AND (r6c4 = 8) AND (r7c2 = 9) AND (r7c7 = 4) AND (r7c8 = 7) AND (r8c2 = 7) AND (r8c3 = 1) AND (r8c5 = 4) AND (r8c7 = 6) AND (r8c9 = 8) AND (r9c1 = 2) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 2) AND (r1c4 = 3) AND (r1c6 = 8) AND (r1c8 = 6) AND (r2c1 = 8) AND (r2c5 = 7) AND (r2c9 = 2) AND (r3c3 = 6) AND (r3c4 = 5) AND (r3c6 = 2) AND (r3c7 = 8) AND (r4c1 = 6) AND (r4c3 = 2) AND (r4c7 = 7) AND (r4c9 = 3) AND (r5c2 = 9) AND (r5c8 = 2) AND (r6c1 = 3) AND (r6c3 = 5) AND (r6c7 = 9) AND (r6c9 = 4) AND (r7c3 = 7) AND (r7c4 = 2) AND (r7c6 = 1) AND (r7c7 = 6) AND (r8c1 = 5) AND (r8c5 = 6) AND (r8c9 = 1) AND (r9c2 = 6) AND (r9c4 = 4) AND (r9c6 = 5) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 2) AND (r1c3 = 4) AND (r1c8 = 3) AND (r1c9 = 1) AND (r2c1 = 9) AND (r2c3 = 6) AND (r2c4 = 4) AND (r2c5 = 5) AND (r3c3 = 3) AND (r3c5 = 7) AND (r3c8 = 6) AND (r5c1 = 4) AND (r5c8 = 7) AND (r5c9 = 9) AND (r6c4 = 5) AND (r6c5 = 6) AND (r7c1 = 1) AND (r7c4 = 2) AND (r8c1 = 6) AND (r8c2 = 7) AND (r8c5 = 4) AND (r9c5 = 9) AND (r9c6 = 7) AND (r9c8 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 6) AND (r1c7 = 4) AND (r2c1 = 9) AND (r2c3 = 3) AND (r3c4 = 4) AND (r3c8 = 2) AND (r4c9 = 9) AND (r5c1 = 2) AND (r5c7 = 3) AND (r6c5 = 3) AND (r6c6 = 1) AND (r6c7 = 7) AND (r7c1 = 5) AND (r7c2 = 9) AND (r7c3 = 7) AND (r8c1 = 4) AND (r8c4 = 9) AND (r9c2 = 2) AND (r9c7 = 6) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 5) AND (r1c4 = 7) AND (r1c8 = 3) AND (r2c2 = 8) AND (r2c6 = 9) AND (r2c9 = 5) AND (r3c4 = 1) AND (r3c7 = 6) AND (r3c9 = 2) AND (r4c8 = 9) AND (r5c5 = 6) AND (r6c4 = 3) AND (r6c6 = 1) AND (r7c2 = 7) AND (r7c8 = 8) AND (r8c1 = 6) AND (r8c4 = 2) AND (r8c5 = 8) AND (r8c7 = 3) AND (r9c1 = 1) AND (r9c2 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 7) AND (r2c2 = 4) AND (r2c7 = 1) AND (r2c9 = 3) AND (r3c6 = 9) AND (r3c8 = 6) AND (r3c9 = 5) AND (r4c3 = 4) AND (r5c2 = 3) AND (r5c3 = 7) AND (r5c4 = 2) AND (r5c8 = 9) AND (r6c4 = 1) AND (r7c1 = 7) AND (r7c5 = 1) AND (r7c7 = 6) AND (r8c3 = 5) AND (r8c6 = 7) AND (r8c7 = 2) AND (r9c5 = 6) AND (r9c6 = 5) AND (r9c8 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 2) AND (r1c5 = 3) AND (r1c8 = 5) AND (r2c2 = 8) AND (r2c9 = 1) AND (r3c2 = 9) AND (r4c1 = 5) AND (r4c6 = 1) AND (r4c8 = 3) AND (r5c5 = 8) AND (r5c7 = 9) AND (r6c1 = 2) AND (r7c2 = 4) AND (r7c4 = 6) AND (r7c7 = 8) AND (r8c1 = 7) AND (r8c4 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 6) AND (r1c5 = 4) AND (r1c6 = 1) AND (r1c7 = 8) AND (r1c9 = 5) AND (r2c3 = 8) AND (r2c6 = 2) AND (r2c7 = 4) AND (r2c9 = 1) AND (r3c1 = 1) AND (r3c3 = 4) AND (r3c4 = 5) AND (r3c5 = 8) AND (r3c8 = 6) AND (r4c3 = 1) AND (r4c5 = 3) AND (r4c9 = 4) AND (r6c6 = 9) AND (r6c9 = 3) AND (r7c2 = 2) AND (r7c3 = 6) AND (r8c1 = 5) AND (r8c3 = 9) AND (r8c5 = 1) AND (r8c6 = 4) AND (r8c8 = 2) AND (r8c9 = 6) AND (r9c1 = 4) AND (r9c5 = 6) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 3) AND (r1c4 = 2) AND (r2c1 = 5) AND (r2c5 = 8) AND (r2c7 = 6) AND (r2c9 = 4) AND (r3c9 = 9) AND (r4c1 = 3) AND (r4c4 = 4) AND (r4c5 = 5) AND (r5c3 = 8) AND (r5c4 = 1) AND (r5c5 = 9) AND (r5c6 = 6) AND (r6c1 = 4) AND (r6c5 = 3) AND (r6c7 = 1) AND (r6c9 = 6) AND (r7c1 = 1) AND (r7c4 = 6) AND (r7c7 = 9) AND (r7c8 = 5) AND (r7c9 = 8) AND (r8c4 = 5) AND (r9c1 = 8) AND (r9c2 = 6) AND (r9c7 = 4) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 6) AND (r1c3 = 4) AND (r1c4 = 3) AND (r1c5 = 1) AND (r1c9 = 5) AND (r2c2 = 2) AND (r2c5 = 5) AND (r2c7 = 6) AND (r2c9 = 4) AND (r3c3 = 8) AND (r3c5 = 6) AND (r3c6 = 4) AND (r3c8 = 2) AND (r4c3 = 1) AND (r4c7 = 9) AND (r4c9 = 2) AND (r5c2 = 3) AND (r6c1 = 8) AND (r6c5 = 2) AND (r6c6 = 6) AND (r6c9 = 1) AND (r7c4 = 5) AND (r7c5 = 9) AND (r8c1 = 3) AND (r8c6 = 8) AND (r9c1 = 9) AND (r9c5 = 4) AND (r9c6 = 3) AND (r9c8 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 1) AND (r1c8 = 7) AND (r1c9 = 3) AND (r2c4 = 5) AND (r2c5 = 6) AND (r2c7 = 8) AND (r2c8 = 4) AND (r3c4 = 3) AND (r3c6 = 8) AND (r3c7 = 6) AND (r4c5 = 5) AND (r4c6 = 2) AND (r4c7 = 7) AND (r4c9 = 6) AND (r5c4 = 7) AND (r5c5 = 1) AND (r5c8 = 3) AND (r7c1 = 2) AND (r7c2 = 7) AND (r7c8 = 6) AND (r7c9 = 8) AND (r8c2 = 4) AND (r8c3 = 5) AND (r8c4 = 1) AND (r9c1 = 6) AND (r9c2 = 8) AND (r9c3 = 3) AND (r9c6 = 7) AND (r9c9 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c5 = 5) AND (r1c8 = 1) AND (r2c1 = 5) AND (r2c2 = 8) AND (r3c5 = 7) AND (r4c4 = 7) AND (r4c5 = 2) AND (r4c6 = 4) AND (r4c7 = 1) AND (r4c8 = 8) AND (r5c1 = 1) AND (r5c5 = 8) AND (r5c9 = 9) AND (r6c2 = 7) AND (r6c4 = 1) AND (r6c5 = 3) AND (r6c8 = 4) AND (r7c1 = 3) AND (r7c3 = 2) AND (r7c5 = 9) AND (r7c7 = 8) AND (r7c8 = 5) AND (r7c9 = 4) AND (r8c2 = 9) AND (r8c3 = 7) AND (r8c7 = 2) AND (r9c1 = 8) AND (r9c3 = 5) AND (r9c6 = 2) AND (r9c8 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c6 = 7) AND (r1c9 = 2) AND (r2c1 = 5) AND (r2c2 = 2) AND (r2c4 = 9) AND (r2c5 = 3) AND (r2c7 = 4) AND (r3c4 = 5) AND (r3c9 = 7) AND (r4c1 = 9) AND (r4c2 = 3) AND (r4c9 = 4) AND (r5c9 = 1) AND (r6c6 = 1) AND (r6c7 = 3) AND (r7c3 = 4) AND (r7c5 = 2) AND (r8c1 = 2) AND (r8c2 = 9) AND (r8c5 = 7) AND (r9c1 = 1) AND (r9c5 = 8) AND (r9c6 = 5) AND (r9c8 = 2) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c7 = 7) AND (r1c8 = 5) AND (r1c9 = 3) AND (r2c2 = 7) AND (r2c3 = 9) AND (r2c6 = 3) AND (r2c7 = 2) AND (r2c8 = 1) AND (r3c3 = 5) AND (r4c5 = 2) AND (r5c3 = 4) AND (r5c5 = 3) AND (r5c7 = 1) AND (r5c9 = 7) AND (r6c1 = 3) AND (r6c3 = 6) AND (r6c4 = 1) AND (r6c7 = 4) AND (r6c8 = 2) AND (r7c1 = 2) AND (r7c3 = 3) AND (r7c6 = 6) AND (r7c7 = 5) AND (r7c9 = 1) AND (r8c2 = 6) AND (r8c3 = 7) AND (r8c5 = 1) AND (r8c8 = 4) AND (r8c9 = 2) AND (r9c7 = 6) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 3) AND (r1c3 = 7) AND (r1c8 = 5) AND (r2c3 = 9) AND (r2c5 = 6) AND (r2c8 = 1) AND (r3c6 = 1) AND (r3c7 = 3) AND (r4c2 = 7) AND (r5c3 = 1) AND (r5c4 = 2) AND (r5c6 = 7) AND (r5c9 = 5) AND (r6c5 = 3) AND (r6c7 = 8) AND (r6c9 = 6) AND (r7c6 = 3) AND (r8c4 = 7) AND (r8c5 = 8) AND (r9c1 = 6) AND (r9c8 = 9) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 3) AND (r1c7 = 5) AND (r1c8 = 9) AND (r2c2 = 5) AND (r2c3 = 1) AND (r2c5 = 6) AND (r2c6 = 3) AND (r3c3 = 9) AND (r3c5 = 2) AND (r5c2 = 7) AND (r5c3 = 3) AND (r5c5 = 5) AND (r5c8 = 2) AND (r6c3 = 2) AND (r6c7 = 1) AND (r6c8 = 7) AND (r7c2 = 9) AND (r7c4 = 7) AND (r7c6 = 6) AND (r7c7 = 3) AND (r7c8 = 5) AND (r8c1 = 7) AND (r8c2 = 8) AND (r9c5 = 8) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r2c4 = 4) AND (r2c8 = 5) AND (r3c1 = 8) AND (r3c2 = 5) AND (r3c3 = 9) AND (r3c4 = 2) AND (r4c3 = 3) AND (r4c4 = 5) AND (r4c7 = 4) AND (r4c8 = 9) AND (r5c7 = 5) AND (r5c9 = 6) AND (r6c3 = 7) AND (r6c4 = 9) AND (r6c5 = 2) AND (r6c6 = 4) AND (r6c8 = 3) AND (r6c9 = 8) AND (r7c6 = 2) AND (r7c8 = 8) AND (r8c1 = 7) AND (r8c4 = 8) AND (r8c5 = 5) AND (r8c7 = 9) AND (r8c8 = 4) AND (r9c2 = 3) AND (r9c4 = 7) AND (r9c5 = 4) AND (r9c8 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 9) AND (r1c7 = 6) AND (r2c1 = 8) AND (r2c3 = 6) AND (r2c4 = 7) AND (r2c5 = 4) AND (r2c6 = 5) AND (r2c8 = 2) AND (r2c9 = 9) AND (r3c3 = 4) AND (r3c6 = 3) AND (r3c8 = 7) AND (r3c9 = 5) AND (r4c1 = 4) AND (r4c4 = 3) AND (r4c5 = 7) AND (r4c6 = 9) AND (r4c8 = 6) AND (r5c6 = 4) AND (r6c1 = 7) AND (r6c5 = 8) AND (r6c8 = 5) AND (r7c3 = 8) AND (r7c4 = 4) AND (r7c6 = 6) AND (r8c1 = 3) AND (r8c5 = 5) AND (r8c6 = 8) AND (r9c4 = 2) AND (r9c5 = 3) AND (r9c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c5 = 7) AND (r3c3 = 3) AND (r3c5 = 2) AND (r3c8 = 5) AND (r4c2 = 6) AND (r4c5 = 4) AND (r4c9 = 2) AND (r5c3 = 8) AND (r5c4 = 5) AND (r5c6 = 9) AND (r6c4 = 6) AND (r7c1 = 6) AND (r7c8 = 9) AND (r8c3 = 2) AND (r8c5 = 3) AND (r8c9 = 4) AND (r9c1 = 4) AND (r9c2 = 7) AND (r9c4 = 8) AND (r9c7 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 3) AND (r1c4 = 4) AND (r1c6 = 6) AND (r2c2 = 9) AND (r2c7 = 7) AND (r4c1 = 6) AND (r4c3 = 4) AND (r4c4 = 1) AND (r5c5 = 7) AND (r5c7 = 2) AND (r5c9 = 9) AND (r6c7 = 5) AND (r7c5 = 3) AND (r7c8 = 8) AND (r8c1 = 5) AND (r8c2 = 2) AND (r9c4 = 8) AND (r9c8 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 7) AND (r1c5 = 2) AND (r2c2 = 8) AND (r2c6 = 6) AND (r3c6 = 3) AND (r3c9 = 6) AND (r4c3 = 3) AND (r4c5 = 4) AND (r4c7 = 7) AND (r4c8 = 8) AND (r5c1 = 2) AND (r5c5 = 1) AND (r6c2 = 6) AND (r6c9 = 5) AND (r7c4 = 1) AND (r7c7 = 3) AND (r7c8 = 7) AND (r8c5 = 5) AND (r9c3 = 8) AND (r9c6 = 7) AND (r9c8 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c8 = 8) AND (r2c1 = 3) AND (r2c2 = 5) AND (r2c3 = 1) AND (r2c5 = 7) AND (r3c6 = 9) AND (r3c7 = 7) AND (r3c9 = 3) AND (r4c3 = 7) AND (r4c4 = 1) AND (r4c6 = 8) AND (r4c7 = 5) AND (r5c5 = 3) AND (r5c7 = 2) AND (r6c2 = 8) AND (r6c6 = 5) AND (r6c8 = 9) AND (r7c7 = 1) AND (r7c8 = 5) AND (r7c9 = 2) AND (r8c3 = 3) AND (r8c4 = 4) AND (r8c6 = 1) AND (r9c4 = 9) AND (r9c5 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 3) AND (r1c9 = 8) AND (r2c1 = 7) AND (r2c2 = 2) AND (r2c4 = 9) AND (r2c9 = 6) AND (r3c4 = 1) AND (r4c2 = 8) AND (r4c6 = 6) AND (r5c3 = 7) AND (r5c5 = 5) AND (r5c8 = 6) AND (r6c1 = 3) AND (r6c5 = 2) AND (r7c1 = 5) AND (r7c3 = 8) AND (r7c4 = 7) AND (r7c5 = 1) AND (r8c6 = 9) AND (r9c1 = 2) AND (r9c3 = 6) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 5) AND (r1c3 = 2) AND (r1c4 = 9) AND (r2c7 = 8) AND (r3c8 = 4) AND (r3c9 = 6) AND (r4c2 = 1) AND (r4c6 = 2) AND (r4c9 = 3) AND (r5c1 = 3) AND (r5c2 = 7) AND (r6c6 = 4) AND (r7c8 = 7) AND (r8c1 = 6) AND (r8c4 = 5) AND (r8c6 = 1) AND (r9c1 = 4) AND (r9c4 = 3) AND (r9c6 = 9) AND (r9c7 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c5 = 6) AND (r1c6 = 4) AND (r1c8 = 2) AND (r1c9 = 5) AND (r2c2 = 5) AND (r2c6 = 9) AND (r2c9 = 1) AND (r3c5 = 2) AND (r3c8 = 4) AND (r3c9 = 9) AND (r4c1 = 5) AND (r4c3 = 6) AND (r4c6 = 3) AND (r4c8 = 1) AND (r5c1 = 4) AND (r5c3 = 2) AND (r6c2 = 1) AND (r7c1 = 3) AND (r7c2 = 6) AND (r7c3 = 9) AND (r7c4 = 4) AND (r7c8 = 5) AND (r8c3 = 5) AND (r8c6 = 6) AND (r9c1 = 7) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c5 = 6) AND (r1c6 = 5) AND (r1c9 = 7) AND (r2c1 = 5) AND (r2c6 = 3) AND (r2c8 = 6) AND (r2c9 = 8) AND (r3c3 = 8) AND (r3c4 = 4) AND (r3c9 = 9) AND (r4c3 = 2) AND (r5c5 = 5) AND (r5c9 = 3) AND (r6c3 = 6) AND (r6c6 = 7) AND (r7c5 = 9) AND (r7c7 = 2) AND (r8c4 = 3) AND (r8c7 = 4) AND (r9c1 = 6) AND (r9c8 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c4 = 3) AND (r1c8 = 6) AND (r2c5 = 8) AND (r2c7 = 5) AND (r3c2 = 1) AND (r4c1 = 8) AND (r4c3 = 9) AND (r4c4 = 6) AND (r4c7 = 4) AND (r5c4 = 1) AND (r5c6 = 2) AND (r6c1 = 5) AND (r7c4 = 7) AND (r7c8 = 3) AND (r7c9 = 2) AND (r8c1 = 4) AND (r8c5 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 4) AND (r1c8 = 6) AND (r2c4 = 1) AND (r2c5 = 2) AND (r2c6 = 9) AND (r2c8 = 8) AND (r2c9 = 4) AND (r3c3 = 2) AND (r4c3 = 5) AND (r4c7 = 4) AND (r5c2 = 2) AND (r5c4 = 4) AND (r5c5 = 1) AND (r5c7 = 8) AND (r5c8 = 5) AND (r6c2 = 6) AND (r6c4 = 5) AND (r6c6 = 8) AND (r6c8 = 2) AND (r7c1 = 2) AND (r7c2 = 1) AND (r7c3 = 6) AND (r7c6 = 5) AND (r8c2 = 8) AND (r8c4 = 2) AND (r8c5 = 3) AND (r9c2 = 3) AND (r9c3 = 4) AND (r9c4 = 8) AND (r9c6 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 8) AND (r1c7 = 1) AND (r1c9 = 4) AND (r2c1 = 7) AND (r2c2 = 3) AND (r4c5 = 7) AND (r4c6 = 2) AND (r4c7 = 6) AND (r5c2 = 1) AND (r5c3 = 3) AND (r7c3 = 4) AND (r7c4 = 3) AND (r7c5 = 1) AND (r8c1 = 2) AND (r8c7 = 5) AND (r8c8 = 7) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 9) AND (r1c5 = 4) AND (r1c8 = 8) AND (r2c2 = 4) AND (r2c9 = 7) AND (r3c4 = 6) AND (r3c9 = 2) AND (r4c3 = 5) AND (r4c7 = 7) AND (r4c8 = 4) AND (r5c1 = 9) AND (r5c2 = 6) AND (r5c7 = 5) AND (r6c4 = 2) AND (r7c2 = 5) AND (r7c5 = 2) AND (r7c9 = 8) AND (r8c3 = 4) AND (r8c5 = 8) AND (r8c6 = 3) AND (r9c2 = 8) AND (r9c4 = 9) AND (r9c5 = 7) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 2) AND (r1c5 = 6) AND (r1c8 = 8) AND (r2c1 = 9) AND (r2c3 = 4) AND (r4c2 = 8) AND (r4c4 = 5) AND (r4c8 = 6) AND (r5c1 = 7) AND (r5c6 = 9) AND (r6c9 = 1) AND (r7c2 = 2) AND (r7c4 = 6) AND (r8c5 = 3) AND (r8c7 = 9) AND (r9c1 = 1) AND (r9c7 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 4) AND (r1c3 = 8) AND (r1c4 = 9) AND (r1c6 = 7) AND (r1c7 = 1) AND (r3c4 = 4) AND (r3c5 = 3) AND (r3c6 = 1) AND (r4c6 = 4) AND (r5c5 = 9) AND (r5c7 = 7) AND (r6c1 = 6) AND (r6c5 = 2) AND (r6c6 = 3) AND (r7c2 = 7) AND (r7c6 = 8) AND (r7c7 = 3) AND (r7c9 = 9) AND (r8c1 = 1) AND (r8c3 = 3) AND (r8c5 = 7) AND (r8c6 = 2) AND (r8c7 = 8) AND (r8c9 = 4) AND (r9c2 = 8) AND (r9c3 = 4) AND (r9c7 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 7) AND (r1c3 = 5) AND (r1c7 = 8) AND (r1c8 = 2) AND (r2c1 = 2) AND (r2c2 = 9) AND (r2c3 = 8) AND (r2c4 = 7) AND (r3c1 = 4) AND (r3c2 = 3) AND (r3c8 = 5) AND (r3c9 = 9) AND (r4c1 = 8) AND (r4c4 = 3) AND (r4c5 = 4) AND (r4c6 = 6) AND (r5c4 = 2) AND (r5c7 = 3) AND (r6c5 = 5) AND (r6c6 = 7) AND (r7c5 = 6) AND (r7c6 = 4) AND (r8c4 = 8) AND (r8c6 = 9) AND (r8c8 = 4) AND (r9c4 = 5) AND (r9c5 = 3) AND (r9c7 = 6) AND (r9c8 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 1) AND (r1c8 = 8) AND (r2c8 = 6) AND (r3c3 = 8) AND (r3c4 = 4) AND (r3c7 = 1) AND (r4c1 = 5) AND (r4c3 = 6) AND (r4c7 = 4) AND (r5c5 = 9) AND (r5c8 = 5) AND (r5c9 = 7) AND (r6c5 = 8) AND (r6c6 = 4) AND (r7c4 = 8) AND (r7c6 = 7) AND (r7c7 = 2) AND (r8c2 = 2) AND (r8c3 = 7) AND (r8c5 = 1) AND (r9c2 = 5) AND (r9c4 = 6) AND (r9c6 = 2) AND (r9c7 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 6) AND (r1c4 = 3) AND (r1c6 = 1) AND (r2c5 = 8) AND (r2c9 = 1) AND (r3c2 = 8) AND (r3c4 = 9) AND (r3c5 = 5) AND (r3c6 = 7) AND (r3c8 = 3) AND (r4c1 = 9) AND (r4c3 = 8) AND (r4c5 = 3) AND (r4c6 = 4) AND (r4c8 = 6) AND (r5c6 = 9) AND (r6c4 = 1) AND (r6c5 = 7) AND (r6c6 = 8) AND (r6c8 = 9) AND (r6c9 = 5) AND (r7c1 = 8) AND (r7c2 = 6) AND (r7c6 = 5) AND (r7c7 = 7) AND (r7c8 = 1) AND (r8c1 = 7) AND (r8c3 = 1) AND (r8c6 = 3) AND (r8c7 = 5) AND (r8c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c8 = 4) AND (r2c1 = 6) AND (r2c4 = 3) AND (r2c5 = 8) AND (r2c9 = 7) AND (r3c4 = 7) AND (r3c5 = 9) AND (r3c6 = 6) AND (r4c4 = 6) AND (r4c8 = 3) AND (r5c5 = 1) AND (r6c3 = 7) AND (r6c4 = 4) AND (r6c9 = 2) AND (r7c2 = 4) AND (r7c4 = 8) AND (r7c9 = 6) AND (r8c1 = 3) AND (r8c2 = 1) AND (r9c2 = 9) AND (r9c7 = 2) AND (r9c8 = 1) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 1) AND (r1c7 = 6) AND (r2c2 = 4) AND (r2c3 = 3) AND (r2c8 = 8) AND (r2c9 = 5) AND (r3c1 = 6) AND (r3c4 = 5) AND (r3c9 = 2) AND (r4c6 = 3) AND (r4c7 = 2) AND (r5c3 = 5) AND (r5c5 = 1) AND (r5c6 = 7) AND (r5c8 = 6) AND (r5c9 = 8) AND (r6c4 = 8) AND (r6c6 = 5) AND (r6c9 = 1) AND (r7c3 = 2) AND (r7c6 = 6) AND (r7c7 = 1) AND (r7c8 = 3) AND (r7c9 = 4) AND (r8c1 = 4) AND (r8c6 = 1) AND (r8c8 = 2) AND (r8c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c5 = 2) AND (r1c6 = 9) AND (r1c7 = 3) AND (r1c8 = 6) AND (r2c1 = 3) AND (r2c2 = 8) AND (r2c4 = 1) AND (r2c5 = 4) AND (r2c8 = 2) AND (r3c2 = 9) AND (r4c2 = 1) AND (r4c3 = 9) AND (r4c4 = 8) AND (r4c7 = 4) AND (r5c4 = 4) AND (r5c5 = 9) AND (r5c9 = 7) AND (r6c6 = 3) AND (r7c1 = 8) AND (r7c3 = 6) AND (r8c3 = 7) AND (r8c7 = 8) AND (r9c6 = 2) AND (r9c8 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 1) AND (r1c8 = 6) AND (r2c1 = 6) AND (r2c5 = 7) AND (r2c6 = 2) AND (r3c9 = 9) AND (r4c1 = 1) AND (r4c2 = 8) AND (r4c4 = 2) AND (r4c7 = 5) AND (r6c6 = 5) AND (r6c8 = 9) AND (r6c9 = 4) AND (r7c1 = 7) AND (r7c2 = 5) AND (r7c7 = 9) AND (r8c1 = 4) AND (r8c6 = 6) AND (r8c7 = 8) AND (r8c8 = 5) AND (r9c3 = 6) AND (r9c5 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 6) AND (r1c6 = 7) AND (r1c7 = 5) AND (r2c5 = 5) AND (r2c8 = 6) AND (r2c9 = 4) AND (r3c2 = 5) AND (r3c5 = 6) AND (r3c7 = 9) AND (r3c8 = 8) AND (r3c9 = 1) AND (r4c1 = 1) AND (r5c3 = 7) AND (r5c4 = 9) AND (r5c9 = 2) AND (r6c2 = 9) AND (r6c7 = 1) AND (r7c3 = 4) AND (r7c5 = 1) AND (r7c6 = 5) AND (r7c9 = 9) AND (r8c1 = 8) AND (r8c5 = 7) AND (r8c9 = 6) AND (r9c6 = 2) AND (r9c8 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c5 = 6) AND (r2c2 = 2) AND (r2c3 = 7) AND (r2c5 = 9) AND (r2c6 = 1) AND (r2c9 = 5) AND (r3c3 = 3) AND (r3c4 = 7) AND (r3c6 = 8) AND (r4c8 = 3) AND (r5c1 = 5) AND (r5c3 = 6) AND (r5c5 = 2) AND (r5c6 = 9) AND (r5c7 = 7) AND (r6c1 = 2) AND (r6c3 = 1) AND (r6c6 = 7) AND (r7c1 = 3) AND (r7c3 = 9) AND (r7c6 = 6) AND (r7c7 = 1) AND (r7c8 = 2) AND (r8c2 = 6) AND (r8c3 = 5) AND (r8c5 = 1) AND (r8c6 = 2) AND (r9c1 = 1) AND (r9c4 = 9) AND (r9c5 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 3) AND (r1c7 = 7) AND (r1c8 = 6) AND (r2c1 = 8) AND (r2c5 = 2) AND (r2c6 = 6) AND (r2c8 = 5) AND (r3c1 = 4) AND (r3c2 = 5) AND (r4c8 = 1) AND (r5c3 = 2) AND (r5c4 = 8) AND (r5c6 = 5) AND (r5c8 = 3) AND (r5c9 = 7) AND (r6c9 = 8) AND (r7c1 = 2) AND (r7c3 = 8) AND (r7c4 = 6) AND (r8c2 = 3) AND (r8c4 = 5) AND (r8c7 = 6) AND (r8c8 = 2) AND (r9c3 = 7) AND (r9c6 = 2) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r2c2 = 1) AND (r2c5 = 8) AND (r2c6 = 6) AND (r2c7 = 4) AND (r3c2 = 4) AND (r4c3 = 8) AND (r4c7 = 1) AND (r4c8 = 3) AND (r5c1 = 5) AND (r5c2 = 3) AND (r6c2 = 7) AND (r6c3 = 1) AND (r6c5 = 3) AND (r6c7 = 5) AND (r7c3 = 7) AND (r7c4 = 4) AND (r7c8 = 1) AND (r8c2 = 5) AND (r8c3 = 4) AND (r8c4 = 7) AND (r8c5 = 9) AND (r8c7 = 6) AND (r8c9 = 8) AND (r9c2 = 6) AND (r9c3 = 9) AND (r9c4 = 8) AND (r9c5 = 5) AND (r9c6 = 1) AND (r9c7 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 7) AND (r1c3 = 8) AND (r1c5 = 2) AND (r2c8 = 9) AND (r2c9 = 1) AND (r3c1 = 3) AND (r4c2 = 4) AND (r4c3 = 6) AND (r5c5 = 3) AND (r5c7 = 7) AND (r6c4 = 5) AND (r7c2 = 5) AND (r7c4 = 9) AND (r7c6 = 6) AND (r8c4 = 4) AND (r8c8 = 1) AND (r9c1 = 2) AND (r9c7 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 3) AND (r1c9 = 2) AND (r2c3 = 8) AND (r3c5 = 5) AND (r4c9 = 4) AND (r5c2 = 5) AND (r5c5 = 7) AND (r5c8 = 2) AND (r6c2 = 7) AND (r6c4 = 3) AND (r6c5 = 8) AND (r6c6 = 4) AND (r6c8 = 5) AND (r7c2 = 9) AND (r7c3 = 7) AND (r7c6 = 8) AND (r7c9 = 5) AND (r8c2 = 8) AND (r8c3 = 2) AND (r8c5 = 1) AND (r8c6 = 7) AND (r8c8 = 4) AND (r9c2 = 1) AND (r9c3 = 5) AND (r9c4 = 4) AND (r9c5 = 2) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 7) AND (r1c6 = 5) AND (r2c1 = 6) AND (r2c9 = 4) AND (r3c1 = 8) AND (r3c2 = 5) AND (r3c6 = 7) AND (r4c6 = 8) AND (r4c9 = 6) AND (r5c1 = 9) AND (r5c2 = 6) AND (r5c5 = 4) AND (r5c7 = 5) AND (r6c3 = 1) AND (r6c6 = 3) AND (r6c7 = 8) AND (r7c3 = 4) AND (r7c5 = 7) AND (r8c1 = 3) AND (r8c4 = 8) AND (r8c7 = 9) AND (r8c9 = 7) AND (r9c2 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 8) AND (r1c5 = 7) AND (r1c8 = 2) AND (r2c7 = 6) AND (r2c9 = 4) AND (r3c3 = 6) AND (r3c4 = 9) AND (r3c6 = 5) AND (r3c7 = 3) AND (r4c4 = 5) AND (r4c6 = 7) AND (r5c5 = 9) AND (r5c8 = 8) AND (r5c9 = 2) AND (r6c7 = 5) AND (r7c1 = 2) AND (r7c2 = 3) AND (r7c6 = 4) AND (r7c9 = 9) AND (r8c1 = 4) AND (r8c4 = 7) AND (r8c5 = 6) AND (r8c9 = 5) AND (r9c1 = 5) AND (r9c5 = 3) AND (r9c6 = 9) AND (r9c8 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 6) AND (r1c4 = 8) AND (r1c6 = 9) AND (r1c9 = 5) AND (r2c1 = 5) AND (r2c6 = 4) AND (r3c1 = 9) AND (r3c2 = 2) AND (r3c7 = 6) AND (r4c3 = 1) AND (r4c7 = 3) AND (r5c3 = 3) AND (r5c5 = 8) AND (r5c9 = 6) AND (r6c1 = 6) AND (r6c4 = 1) AND (r6c5 = 9) AND (r6c8 = 5) AND (r6c9 = 8) AND (r7c9 = 3) AND (r8c6 = 2) AND (r9c4 = 6) AND (r9c7 = 1) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 6) AND (r1c9 = 7) AND (r2c4 = 7) AND (r2c5 = 9) AND (r2c8 = 8) AND (r2c9 = 3) AND (r3c5 = 8) AND (r3c7 = 5) AND (r3c8 = 4) AND (r4c2 = 4) AND (r4c3 = 3) AND (r4c5 = 1) AND (r4c9 = 5) AND (r5c3 = 5) AND (r5c8 = 6) AND (r6c2 = 6) AND (r6c5 = 3) AND (r6c7 = 4) AND (r7c1 = 6) AND (r7c4 = 3) AND (r7c6 = 9) AND (r7c7 = 8) AND (r8c6 = 5) AND (r8c8 = 9) AND (r9c1 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 2) AND (r2c2 = 4) AND (r2c6 = 6) AND (r2c8 = 7) AND (r2c9 = 1) AND (r3c3 = 9) AND (r3c4 = 3) AND (r3c7 = 4) AND (r4c4 = 9) AND (r4c5 = 4) AND (r5c3 = 6) AND (r5c6 = 1) AND (r5c9 = 7) AND (r6c3 = 1) AND (r6c5 = 2) AND (r6c6 = 7) AND (r7c1 = 7) AND (r7c3 = 4) AND (r7c4 = 1) AND (r7c5 = 6) AND (r7c8 = 9) AND (r7c9 = 5) AND (r8c1 = 9) AND (r9c1 = 6) AND (r9c2 = 1) AND (r9c5 = 5) AND (r9c8 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 7) AND (r1c6 = 1) AND (r1c8 = 4) AND (r2c1 = 8) AND (r2c3 = 9) AND (r2c4 = 2) AND (r2c8 = 1) AND (r3c4 = 8) AND (r3c6 = 7) AND (r3c7 = 2) AND (r3c9 = 5) AND (r4c1 = 5) AND (r5c3 = 4) AND (r5c4 = 6) AND (r5c8 = 8) AND (r6c3 = 7) AND (r6c4 = 4) AND (r7c4 = 9) AND (r7c8 = 6) AND (r7c9 = 8) AND (r8c1 = 9) AND (r8c3 = 5) AND (r8c4 = 1) AND (r8c6 = 8) AND (r8c7 = 4) AND (r8c8 = 7) AND (r9c1 = 4) AND (r9c3 = 8) AND (r9c5 = 2) AND (r9c8 = 5) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c3 = 8) AND (r1c9 = 4) AND (r2c1 = 6) AND (r2c3 = 2) AND (r2c7 = 5) AND (r2c8 = 8) AND (r3c1 = 5) AND (r3c2 = 4) AND (r3c5 = 2) AND (r3c7 = 1) AND (r3c8 = 6) AND (r3c9 = 7) AND (r4c7 = 8) AND (r4c8 = 4) AND (r5c1 = 2) AND (r5c7 = 7) AND (r5c9 = 5) AND (r6c1 = 4) AND (r6c2 = 8) AND (r6c3 = 5) AND (r6c6 = 1) AND (r6c8 = 2) AND (r7c1 = 7) AND (r7c4 = 3) AND (r7c6 = 4) AND (r8c9 = 2) AND (r9c1 = 8) AND (r9c2 = 5) AND (r9c6 = 6) AND (r9c7 = 4) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 5) AND (r1c9 = 3) AND (r2c3 = 6) AND (r2c6 = 1) AND (r2c8 = 8) AND (r3c4 = 4) AND (r3c7 = 6) AND (r3c9 = 2) AND (r4c9 = 1) AND (r5c4 = 9) AND (r5c6 = 8) AND (r5c7 = 5) AND (r6c5 = 3) AND (r6c6 = 6) AND (r6c7 = 8) AND (r7c1 = 4) AND (r7c7 = 1) AND (r7c8 = 9) AND (r8c1 = 8) AND (r8c3 = 5) AND (r8c5 = 1) AND (r8c8 = 4) AND (r9c4 = 6) AND (r9c6 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c5 = 3) AND (r2c3 = 6) AND (r2c4 = 2) AND (r2c6 = 8) AND (r3c4 = 9) AND (r3c5 = 7) AND (r3c9 = 5) AND (r5c1 = 2) AND (r5c3 = 9) AND (r5c4 = 8) AND (r5c6 = 3) AND (r6c4 = 6) AND (r6c6 = 7) AND (r6c9 = 9) AND (r7c1 = 7) AND (r7c2 = 5) AND (r7c8 = 8) AND (r7c9 = 4) AND (r8c2 = 4) AND (r8c3 = 8) AND (r8c5 = 5) AND (r8c7 = 6) AND (r8c9 = 3) AND (r9c3 = 2) AND (r9c8 = 5) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 1) AND (r1c5 = 2) AND (r2c4 = 1) AND (r2c9 = 8) AND (r3c2 = 8) AND (r3c4 = 3) AND (r3c6 = 7) AND (r3c8 = 1) AND (r4c2 = 5) AND (r4c3 = 7) AND (r4c8 = 3) AND (r5c3 = 2) AND (r5c7 = 6) AND (r6c1 = 8) AND (r6c7 = 5) AND (r6c8 = 7) AND (r6c9 = 4) AND (r7c2 = 7) AND (r7c9 = 3) AND (r8c3 = 4) AND (r8c4 = 7) AND (r8c7 = 1) AND (r8c8 = 2) AND (r9c1 = 2) AND (r9c3 = 5) AND (r9c7 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c2 = 1) AND (r1c6 = 3) AND (r1c7 = 9) AND (r2c2 = 6) AND (r2c8 = 8) AND (r2c9 = 2) AND (r3c1 = 2) AND (r3c4 = 7) AND (r3c7 = 3) AND (r4c2 = 8) AND (r4c5 = 3) AND (r4c6 = 6) AND (r5c2 = 9) AND (r5c5 = 1) AND (r5c7 = 4) AND (r5c8 = 3) AND (r6c3 = 6) AND (r6c6 = 9) AND (r7c3 = 2) AND (r8c5 = 8) AND (r8c8 = 7) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c5 = 8) AND (r1c7 = 4) AND (r2c1 = 3) AND (r2c9 = 2) AND (r4c1 = 1) AND (r4c3 = 6) AND (r4c4 = 3) AND (r5c7 = 8) AND (r5c8 = 5) AND (r6c1 = 2) AND (r7c2 = 8) AND (r7c3 = 4) AND (r7c8 = 3) AND (r8c4 = 2) AND (r8c6 = 1) AND (r9c5 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 4) AND (r1c3 = 9) AND (r2c6 = 7) AND (r3c2 = 6) AND (r3c7 = 4) AND (r4c1 = 9) AND (r4c2 = 1) AND (r4c4 = 7) AND (r4c8 = 3) AND (r4c9 = 6) AND (r5c4 = 3) AND (r5c5 = 5) AND (r5c7 = 1) AND (r5c8 = 4) AND (r6c1 = 2) AND (r7c4 = 5) AND (r7c8 = 7) AND (r8c2 = 3) AND (r8c3 = 6) AND (r8c5 = 2) AND (r9c2 = 2) AND (r9c4 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c5 = 5) AND (r1c8 = 4) AND (r1c9 = 6) AND (r2c6 = 1) AND (r2c8 = 7) AND (r3c1 = 3) AND (r3c3 = 6) AND (r3c6 = 9) AND (r3c7 = 5) AND (r3c9 = 1) AND (r4c2 = 5) AND (r4c5 = 9) AND (r4c6 = 4) AND (r5c4 = 2) AND (r6c1 = 9) AND (r6c5 = 7) AND (r6c9 = 3) AND (r7c1 = 4) AND (r7c5 = 6) AND (r7c6 = 7) AND (r7c8 = 2) AND (r7c9 = 5) AND (r9c1 = 6) AND (r9c4 = 5) AND (r9c5 = 1) AND (r9c6 = 3) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c4 = 2) AND (r1c6 = 4) AND (r1c8 = 1) AND (r2c1 = 4) AND (r2c2 = 9) AND (r2c4 = 1) AND (r2c6 = 7) AND (r2c8 = 5) AND (r2c9 = 2) AND (r3c5 = 5) AND (r4c1 = 1) AND (r4c2 = 3) AND (r4c8 = 9) AND (r4c9 = 7) AND (r5c3 = 9) AND (r5c7 = 2) AND (r6c1 = 5) AND (r6c2 = 4) AND (r6c8 = 6) AND (r6c9 = 3) AND (r7c5 = 2) AND (r8c1 = 2) AND (r8c2 = 5) AND (r8c4 = 7) AND (r8c6 = 1) AND (r8c8 = 8) AND (r8c9 = 6) AND (r9c2 = 1) AND (r9c4 = 6) AND (r9c6 = 3) AND (r9c8 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 5) AND (r1c6 = 2) AND (r1c9 = 4) AND (r2c1 = 7) AND (r2c3 = 2) AND (r2c6 = 4) AND (r2c7 = 3) AND (r2c8 = 5) AND (r3c2 = 1) AND (r3c6 = 3) AND (r3c7 = 9) AND (r4c1 = 3) AND (r4c3 = 7) AND (r4c4 = 5) AND (r4c6 = 8) AND (r4c7 = 2) AND (r6c7 = 7) AND (r6c9 = 8) AND (r7c2 = 7) AND (r7c3 = 1) AND (r7c5 = 8) AND (r7c6 = 5) AND (r7c7 = 4) AND (r8c1 = 4) AND (r8c3 = 3) AND (r8c9 = 2) AND (r9c1 = 2) AND (r9c3 = 8) AND (r9c5 = 3) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c8 = 1) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 2) AND (r3c5 = 5) AND (r4c4 = 4) AND (r4c8 = 6) AND (r5c3 = 7) AND (r5c7 = 8) AND (r6c2 = 5) AND (r7c5 = 7) AND (r7c7 = 5) AND (r8c1 = 9) AND (r8c2 = 4) AND (r8c4 = 1) AND (r9c2 = 6) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c9 = 1) AND (r2c6 = 4) AND (r2c8 = 8) AND (r3c2 = 4) AND (r3c4 = 6) AND (r3c6 = 1) AND (r3c8 = 2) AND (r4c1 = 5) AND (r4c2 = 6) AND (r4c3 = 2) AND (r4c5 = 7) AND (r4c7 = 3) AND (r4c8 = 4) AND (r5c1 = 1) AND (r5c3 = 7) AND (r5c6 = 3) AND (r5c9 = 2) AND (r6c1 = 4) AND (r6c2 = 3) AND (r6c5 = 6) AND (r6c8 = 7) AND (r7c9 = 7) AND (r8c6 = 6) AND (r8c7 = 8) AND (r8c9 = 4) AND (r9c1 = 3) AND (r9c4 = 8) AND (r9c6 = 7) AND (r9c7 = 2) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 3) AND (r2c1 = 7) AND (r2c7 = 8) AND (r2c8 = 5) AND (r3c2 = 8) AND (r3c4 = 4) AND (r3c5 = 9) AND (r3c8 = 7) AND (r4c3 = 4) AND (r5c2 = 3) AND (r5c4 = 1) AND (r5c5 = 8) AND (r6c1 = 6) AND (r6c3 = 9) AND (r6c9 = 4) AND (r8c3 = 6) AND (r8c5 = 5) AND (r8c9 = 3) AND (r9c5 = 6) AND (r9c9 = 1);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c6 = 4) AND (r1c8 = 8) AND (r1c9 = 6) AND (r2c3 = 6) AND (r2c4 = 3) AND (r2c7 = 7) AND (r3c2 = 4) AND (r3c3 = 8) AND (r3c8 = 3) AND (r3c9 = 5) AND (r4c2 = 9) AND (r4c4 = 4) AND (r5c3 = 1) AND (r6c1 = 4) AND (r6c3 = 5) AND (r6c4 = 9) AND (r6c6 = 6) AND (r7c1 = 7) AND (r7c2 = 8) AND (r7c3 = 4) AND (r7c5 = 6) AND (r7c6 = 9) AND (r7c9 = 3) AND (r8c6 = 3) AND (r9c1 = 6) AND (r9c4 = 1) AND (r9c5 = 4) AND (r9c6 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 5) AND (r1c4 = 9) AND (r1c7 = 1) AND (r2c4 = 4) AND (r2c7 = 9) AND (r3c1 = 6) AND (r3c2 = 3) AND (r3c5 = 2) AND (r3c7 = 5) AND (r4c1 = 4) AND (r4c9 = 6) AND (r5c3 = 1) AND (r5c5 = 3) AND (r6c8 = 3) AND (r6c9 = 4) AND (r7c1 = 7) AND (r7c2 = 2) AND (r7c4 = 6) AND (r8c4 = 7) AND (r9c8 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 2) AND (r1c5 = 1) AND (r1c7 = 4) AND (r2c3 = 3) AND (r2c5 = 9) AND (r2c7 = 2) AND (r2c8 = 5) AND (r3c1 = 7) AND (r3c3 = 5) AND (r4c4 = 9) AND (r4c7 = 6) AND (r4c9 = 3) AND (r5c1 = 9) AND (r6c3 = 2) AND (r6c6 = 5) AND (r7c5 = 2) AND (r7c8 = 4) AND (r8c6 = 9) AND (r8c8 = 2) AND (r8c9 = 7) AND (r9c3 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 3) AND (r1c6 = 5) AND (r2c1 = 4) AND (r2c4 = 8) AND (r2c5 = 6) AND (r2c6 = 9) AND (r2c9 = 5) AND (r3c1 = 8) AND (r4c3 = 9) AND (r4c6 = 2) AND (r4c8 = 5) AND (r4c9 = 6) AND (r5c1 = 1) AND (r5c3 = 2) AND (r5c8 = 3) AND (r6c1 = 6) AND (r6c2 = 8) AND (r6c4 = 9) AND (r6c5 = 3) AND (r6c8 = 2) AND (r6c9 = 4) AND (r7c2 = 3) AND (r7c3 = 8) AND (r7c4 = 6) AND (r7c9 = 9) AND (r8c1 = 5) AND (r9c3 = 6) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c9 = 1) AND (r2c3 = 2) AND (r2c4 = 9) AND (r2c8 = 5) AND (r3c1 = 8) AND (r3c7 = 4) AND (r4c3 = 6) AND (r4c4 = 2) AND (r4c5 = 5) AND (r5c6 = 7) AND (r6c4 = 3) AND (r6c6 = 6) AND (r6c8 = 9) AND (r7c1 = 4) AND (r7c7 = 7) AND (r8c2 = 1) AND (r8c9 = 8) AND (r9c3 = 5) AND (r9c5 = 3) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 3) AND (r1c4 = 5) AND (r1c8 = 8) AND (r2c1 = 7) AND (r2c5 = 2) AND (r3c3 = 9) AND (r3c6 = 7) AND (r4c4 = 2) AND (r4c6 = 1) AND (r5c1 = 5) AND (r5c2 = 2) AND (r6c2 = 4) AND (r6c5 = 8) AND (r6c7 = 7) AND (r7c4 = 3) AND (r7c8 = 2) AND (r8c5 = 9) AND (r8c6 = 8) AND (r8c7 = 3) AND (r9c2 = 1) AND (r9c3 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c2 = 1) AND (r1c3 = 2) AND (r1c5 = 3) AND (r2c1 = 4) AND (r2c7 = 5) AND (r3c4 = 7) AND (r3c7 = 2) AND (r3c8 = 3) AND (r4c1 = 2) AND (r4c4 = 8) AND (r4c5 = 5) AND (r5c1 = 3) AND (r5c4 = 1) AND (r5c5 = 6) AND (r5c6 = 7) AND (r5c7 = 8) AND (r5c9 = 5) AND (r6c4 = 4) AND (r6c8 = 7) AND (r6c9 = 6) AND (r7c1 = 1) AND (r7c5 = 7) AND (r8c2 = 6) AND (r8c3 = 5) AND (r8c9 = 8) AND (r9c9 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c7 = 8) AND (r2c1 = 2) AND (r2c2 = 8) AND (r2c3 = 3) AND (r2c7 = 4) AND (r2c8 = 1) AND (r3c4 = 2) AND (r4c3 = 1) AND (r4c4 = 3) AND (r4c9 = 6) AND (r5c3 = 2) AND (r5c4 = 1) AND (r5c6 = 6) AND (r5c8 = 5) AND (r5c9 = 4) AND (r6c6 = 5) AND (r6c8 = 7) AND (r7c1 = 1) AND (r7c3 = 5) AND (r8c4 = 4) AND (r8c8 = 3) AND (r8c9 = 1) AND (r9c1 = 3) AND (r9c3 = 8) AND (r9c6 = 1) AND (r9c7 = 6) AND (r9c8 = 2) AND (r9c9 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c6 = 5) AND (r1c9 = 1) AND (r2c2 = 6) AND (r2c5 = 7) AND (r2c7 = 2) AND (r3c2 = 1) AND (r3c3 = 7) AND (r4c3 = 3) AND (r4c4 = 5) AND (r4c5 = 2) AND (r5c4 = 8) AND (r5c5 = 3) AND (r5c7 = 1) AND (r5c9 = 4) AND (r7c4 = 7) AND (r7c9 = 5) AND (r8c3 = 2) AND (r8c6 = 1) AND (r8c9 = 3) AND (r9c1 = 3) AND (r9c2 = 4) AND (r9c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 7) AND (r1c4 = 5) AND (r1c6 = 8) AND (r1c8 = 6) AND (r2c1 = 8) AND (r2c5 = 1) AND (r2c9 = 7) AND (r3c2 = 9) AND (r3c8 = 8) AND (r4c3 = 8) AND (r4c4 = 6) AND (r4c6 = 9) AND (r4c7 = 7) AND (r5c2 = 5) AND (r5c3 = 9) AND (r5c4 = 2) AND (r5c6 = 7) AND (r5c7 = 8) AND (r5c8 = 1) AND (r6c3 = 7) AND (r6c4 = 1) AND (r6c6 = 3) AND (r6c7 = 5) AND (r7c2 = 3) AND (r7c8 = 4) AND (r8c1 = 7) AND (r8c5 = 6) AND (r8c9 = 2) AND (r9c2 = 6) AND (r9c4 = 8) AND (r9c6 = 4) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 8) AND (r1c7 = 7) AND (r1c8 = 4) AND (r2c1 = 5) AND (r2c3 = 1) AND (r3c1 = 3) AND (r3c8 = 9) AND (r4c2 = 9) AND (r4c4 = 2) AND (r4c7 = 5) AND (r5c4 = 6) AND (r5c5 = 8) AND (r6c7 = 3) AND (r7c5 = 3) AND (r7c6 = 1) AND (r8c2 = 2) AND (r8c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 3) AND (r1c7 = 5) AND (r1c9 = 9) AND (r2c1 = 9) AND (r2c2 = 8) AND (r2c3 = 6) AND (r2c5 = 2) AND (r2c7 = 3) AND (r3c3 = 2) AND (r3c9 = 1) AND (r4c7 = 1) AND (r4c8 = 7) AND (r5c4 = 5) AND (r5c6 = 7) AND (r7c1 = 7) AND (r7c6 = 3) AND (r7c7 = 8) AND (r7c8 = 6) AND (r8c3 = 8) AND (r8c4 = 2) AND (r8c5 = 6) AND (r9c2 = 5) AND (r9c9 = 3);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 4) AND (r1c9 = 3) AND (r2c2 = 2) AND (r2c5 = 5) AND (r2c9 = 9) AND (r3c2 = 9) AND (r3c3 = 5) AND (r3c5 = 3) AND (r3c8 = 8) AND (r4c4 = 4) AND (r6c1 = 6) AND (r6c6 = 9) AND (r6c7 = 7) AND (r7c1 = 4) AND (r7c4 = 7) AND (r7c7 = 6) AND (r7c8 = 2) AND (r8c4 = 6) AND (r8c9 = 5) AND (r9c1 = 3) AND (r9c4 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 9) AND (r2c5 = 6) AND (r2c8 = 1) AND (r3c6 = 5) AND (r4c2 = 1) AND (r4c6 = 9) AND (r5c1 = 8) AND (r5c5 = 4) AND (r6c1 = 4) AND (r6c2 = 2) AND (r6c4 = 8) AND (r6c8 = 3) AND (r7c4 = 9) AND (r7c7 = 5) AND (r7c9 = 3) AND (r8c2 = 8) AND (r8c3 = 5) AND (r8c4 = 3) AND (r8c9 = 1) AND (r9c4 = 1) AND (r9c6 = 2) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c8 = 1) AND (r2c1 = 3) AND (r2c2 = 2) AND (r2c4 = 9) AND (r2c9 = 5) AND (r3c2 = 8) AND (r3c4 = 4) AND (r3c5 = 5) AND (r4c3 = 2) AND (r4c4 = 5) AND (r4c6 = 3) AND (r5c8 = 5) AND (r5c9 = 9) AND (r6c1 = 7) AND (r6c9 = 3) AND (r7c3 = 7) AND (r8c1 = 5) AND (r8c5 = 4) AND (r8c7 = 1) AND (r9c2 = 9) AND (r9c3 = 1) AND (r9c4 = 3) AND (r9c7 = 5) AND (r9c8 = 2) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c4 = 5) AND (r1c8 = 4) AND (r2c1 = 5) AND (r2c4 = 3) AND (r2c6 = 8) AND (r3c1 = 2) AND (r3c7 = 9) AND (r4c2 = 6) AND (r4c5 = 7) AND (r5c1 = 4) AND (r5c2 = 3) AND (r5c7 = 6) AND (r6c3 = 5) AND (r6c5 = 8) AND (r7c3 = 9) AND (r7c9 = 6) AND (r8c1 = 7) AND (r8c7 = 5) AND (r9c2 = 8) AND (r9c4 = 4) AND (r9c6 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 9) AND (r1c4 = 3) AND (r1c6 = 5) AND (r1c7 = 7) AND (r2c2 = 3) AND (r2c4 = 8) AND (r2c9 = 2) AND (r3c3 = 8) AND (r3c5 = 2) AND (r3c7 = 6) AND (r4c3 = 2) AND (r4c8 = 9) AND (r4c9 = 7) AND (r5c2 = 7) AND (r5c3 = 6) AND (r5c5 = 5) AND (r5c7 = 1) AND (r6c2 = 8) AND (r6c7 = 3) AND (r7c4 = 9) AND (r7c9 = 1) AND (r8c6 = 1) AND (r9c8 = 6);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 1) AND (r1c6 = 6) AND (r1c9 = 7) AND (r2c2 = 2) AND (r2c4 = 5) AND (r2c7 = 8) AND (r3c3 = 9) AND (r3c4 = 7) AND (r3c9 = 6) AND (r4c1 = 7) AND (r4c3 = 5) AND (r5c3 = 1) AND (r5c5 = 3) AND (r5c7 = 2) AND (r5c8 = 9) AND (r7c5 = 9) AND (r7c6 = 5) AND (r8c1 = 2) AND (r8c9 = 3) AND (r9c1 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 2) AND (r1c2 = 9) AND (r1c4 = 1) AND (r1c5 = 4) AND (r2c5 = 5) AND (r2c6 = 8) AND (r3c1 = 1) AND (r3c2 = 8) AND (r3c5 = 6) AND (r3c7 = 5) AND (r4c1 = 8) AND (r4c9 = 2) AND (r5c2 = 1) AND (r5c4 = 7) AND (r5c9 = 6) AND (r6c7 = 7) AND (r6c8 = 9) AND (r7c1 = 4) AND (r7c7 = 2) AND (r7c8 = 1) AND (r8c9 = 9) AND (r9c1 = 7) AND (r9c4 = 2) AND (r9c7 = 4) AND (r9c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 6) AND (r1c3 = 1) AND (r1c5 = 9) AND (r3c1 = 9) AND (r3c3 = 7) AND (r3c5 = 4) AND (r3c8 = 6) AND (r4c3 = 8) AND (r4c8 = 4) AND (r5c1 = 7) AND (r5c2 = 3) AND (r5c3 = 2) AND (r5c8 = 9) AND (r6c1 = 1) AND (r6c8 = 7) AND (r7c2 = 8) AND (r7c3 = 4) AND (r7c4 = 6) AND (r7c5 = 1) AND (r7c9 = 9) AND (r8c1 = 2) AND (r8c3 = 9) AND (r8c5 = 8) AND (r8c6 = 4) AND (r8c7 = 3) AND (r9c5 = 2) AND (r9c6 = 7) AND (r9c8 = 8) AND (r9c9 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 4) AND (r1c6 = 1) AND (r1c8 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 5) AND (r3c5 = 6) AND (r4c4 = 3) AND (r4c9 = 7) AND (r5c3 = 1) AND (r5c7 = 6) AND (r6c1 = 6) AND (r6c6 = 2) AND (r7c5 = 4) AND (r7c7 = 1) AND (r8c1 = 9) AND (r8c2 = 7) AND (r9c2 = 3) AND (r9c4 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c2 = 9) AND (r2c1 = 3) AND (r2c3 = 6) AND (r2c5 = 4) AND (r3c2 = 1) AND (r3c3 = 4) AND (r4c2 = 7) AND (r4c9 = 1) AND (r5c3 = 1) AND (r5c5 = 6) AND (r6c1 = 2) AND (r6c6 = 7) AND (r6c7 = 9) AND (r6c9 = 8) AND (r7c1 = 7) AND (r7c4 = 6) AND (r7c5 = 2) AND (r7c6 = 1) AND (r7c7 = 8) AND (r7c9 = 3) AND (r8c4 = 7) AND (r8c6 = 3) AND (r8c7 = 4) AND (r8c8 = 9) AND (r9c2 = 3) AND (r9c5 = 8) AND (r9c6 = 9) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 4) AND (r2c2 = 4) AND (r2c5 = 7) AND (r2c8 = 3) AND (r2c9 = 6) AND (r3c1 = 2) AND (r3c5 = 3) AND (r3c6 = 6) AND (r3c8 = 8) AND (r4c4 = 1) AND (r4c5 = 4) AND (r4c9 = 7) AND (r5c1 = 1) AND (r5c6 = 3) AND (r5c8 = 6) AND (r6c4 = 6) AND (r6c8 = 2) AND (r7c1 = 3) AND (r7c5 = 5) AND (r7c8 = 1) AND (r8c2 = 5) AND (r8c4 = 7) AND (r8c5 = 8) AND (r8c6 = 2) AND (r9c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c8 = 1) AND (r2c6 = 2) AND (r2c8 = 3) AND (r2c9 = 4) AND (r3c3 = 5) AND (r3c5 = 6) AND (r4c4 = 4) AND (r4c8 = 7) AND (r5c3 = 2) AND (r5c7 = 6) AND (r6c2 = 1) AND (r6c6 = 5) AND (r7c5 = 8) AND (r7c7 = 2) AND (r8c1 = 7) AND (r8c2 = 3) AND (r8c4 = 1) AND (r9c2 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 8) AND (r1c4 = 4) AND (r1c5 = 3) AND (r1c7 = 9) AND (r1c8 = 1) AND (r2c1 = 3) AND (r2c5 = 9) AND (r3c2 = 4) AND (r3c4 = 7) AND (r3c6 = 1) AND (r3c9 = 6) AND (r4c2 = 7) AND (r4c4 = 1) AND (r4c5 = 4) AND (r4c7 = 5) AND (r5c1 = 6) AND (r5c3 = 3) AND (r6c1 = 5) AND (r6c2 = 1) AND (r6c8 = 8) AND (r7c1 = 7) AND (r7c3 = 6) AND (r7c4 = 8) AND (r7c8 = 9) AND (r8c2 = 3) AND (r8c4 = 9) AND (r9c2 = 9) AND (r9c4 = 3) AND (r9c9 = 8);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 7) AND (r1c3 = 1) AND (r1c4 = 2) AND (r1c5 = 5) AND (r1c8 = 8) AND (r2c1 = 8) AND (r2c3 = 6) AND (r2c5 = 7) AND (r2c6 = 4) AND (r2c9 = 5) AND (r3c2 = 9) AND (r3c3 = 4) AND (r3c6 = 6) AND (r3c7 = 7) AND (r5c3 = 8) AND (r5c4 = 6) AND (r5c6 = 5) AND (r5c9 = 9) AND (r6c4 = 8) AND (r6c5 = 2) AND (r6c6 = 1) AND (r6c8 = 4) AND (r6c9 = 6) AND (r7c1 = 6) AND (r7c6 = 8) AND (r7c9 = 1) AND (r8c1 = 1) AND (r8c3 = 9) AND (r8c9 = 7) AND (r9c2 = 4);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 1) AND (r1c5 = 5) AND (r1c7 = 6) AND (r2c1 = 8) AND (r2c3 = 7) AND (r3c1 = 3) AND (r4c4 = 7) AND (r4c6 = 8) AND (r4c8 = 3) AND (r5c2 = 1) AND (r5c7 = 4) AND (r7c2 = 4) AND (r7c5 = 6) AND (r7c7 = 2) AND (r8c1 = 5) AND (r8c8 = 8) AND (r9c4 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 7) AND (r1c5 = 9) AND (r1c7 = 2) AND (r2c3 = 6) AND (r2c7 = 3) AND (r2c9 = 8) AND (r3c2 = 5) AND (r3c5 = 8) AND (r3c6 = 3) AND (r3c8 = 7) AND (r3c9 = 9) AND (r4c3 = 4) AND (r4c4 = 3) AND (r4c7 = 7) AND (r4c8 = 6) AND (r5c7 = 8) AND (r5c9 = 2) AND (r6c1 = 5) AND (r6c2 = 6) AND (r8c2 = 8) AND (r8c3 = 9) AND (r8c4 = 5) AND (r8c6 = 6) AND (r9c1 = 3) AND (r9c2 = 2) AND (r9c9 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c3 = 2) AND (r1c4 = 8) AND (r1c6 = 1) AND (r1c7 = 5) AND (r1c8 = 4) AND (r2c5 = 3) AND (r3c4 = 4) AND (r3c5 = 6) AND (r3c6 = 5) AND (r4c1 = 8) AND (r4c3 = 3) AND (r4c6 = 9) AND (r4c7 = 4) AND (r4c9 = 5) AND (r5c2 = 5) AND (r5c6 = 3) AND (r5c9 = 1) AND (r6c3 = 6) AND (r6c7 = 3) AND (r7c4 = 2) AND (r7c6 = 4) AND (r8c3 = 5) AND (r8c5 = 1) AND (r8c6 = 8) AND (r8c7 = 6) AND (r8c8 = 2) AND (r9c3 = 9) AND (r9c5 = 5);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c4 = 1) AND (r2c1 = 1) AND (r2c2 = 2) AND (r2c5 = 9) AND (r2c8 = 7) AND (r3c5 = 7) AND (r3c6 = 6) AND (r5c2 = 6) AND (r5c5 = 3) AND (r5c6 = 9) AND (r5c8 = 1) AND (r6c1 = 5) AND (r6c3 = 9) AND (r6c4 = 4) AND (r6c6 = 7) AND (r6c8 = 2) AND (r7c3 = 2) AND (r7c6 = 3) AND (r7c7 = 4) AND (r7c8 = 5) AND (r8c1 = 6) AND (r8c4 = 7) AND (r8c5 = 2) AND (r8c8 = 3) AND (r8c9 = 9) AND (r9c2 = 7) AND (r9c4 = 9) AND (r9c5 = 4) AND (r9c6 = 1) AND (r9c8 = 6) AND (r9c9 = 2);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 2) AND (r2c3 = 5) AND (r2c5 = 3) AND (r2c6 = 9) AND (r2c7 = 8) AND (r3c1 = 8) AND (r3c2 = 4) AND (r3c3 = 9) AND (r3c5 = 7) AND (r4c3 = 7) AND (r4c4 = 3) AND (r4c5 = 2) AND (r4c6 = 6) AND (r5c4 = 7) AND (r5c5 = 4) AND (r5c6 = 8) AND (r5c9 = 3) AND (r6c6 = 5) AND (r7c3 = 3) AND (r7c5 = 6) AND (r7c9 = 5) AND (r8c2 = 5) AND (r8c4 = 9) AND (r8c8 = 6) AND (r9c1 = 4) AND (r9c3 = 8) AND (r9c5 = 5) AND (r9c6 = 7) AND (r9c8 = 3) AND (r9c9 = 9);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 1) AND (r1c2 = 9) AND (r2c1 = 8) AND (r2c5 = 7) AND (r2c8 = 1) AND (r2c9 = 6) AND (r3c2 = 7) AND (r3c4 = 2) AND (r3c7 = 5) AND (r3c9 = 3) AND (r4c8 = 2) AND (r4c9 = 7) AND (r5c2 = 3) AND (r5c9 = 8) AND (r6c1 = 9) AND (r6c3 = 5) AND (r7c2 = 1) AND (r7c3 = 8) AND (r7c6 = 2) AND (r7c8 = 3) AND (r8c9 = 2) AND (r9c2 = 6) AND (r9c5 = 1) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c1 = 8) AND (r1c3 = 5) AND (r1c9 = 2) AND (r2c4 = 9) AND (r2c6 = 1) AND (r3c1 = 3) AND (r4c2 = 6) AND (r4c4 = 7) AND (r4c7 = 4) AND (r5c1 = 2) AND (r5c5 = 5) AND (r6c8 = 6) AND (r7c4 = 3) AND (r7c5 = 8) AND (r8c2 = 1) AND (r8c7 = 9) AND (r9c2 = 4) AND (r9c8 = 7);
SELECT * FROM sudoku_memory_combined_view WHERE (r1c2 = 8) AND (r2c1 = 1) AND (r2c3 = 7) AND (r2c7 = 8) AND (r2c9 = 3) AND (r3c6 = 6) AND (r3c9 = 1) AND (r4c2 = 2) AND (r5c1 = 3) AND (r5c5 = 1) AND (r6c3 = 8) AND (r6c4 = 5) AND (r6c7 = 6) AND (r6c8 = 9) AND (r7c5 = 3) AND (r7c6 = 7) AND (r7c7 = 9) AND (r8c6 = 1) AND (r9c1 = 5) AND (r9c2 = 9);
UPDATE tests SET fin = NOW() WHERE fin IS NULL;
SELECT TO_SECONDS(fin) - TO_SECONDS(debut) FROM tests;
```

6. Gosser à la main!

Maintenant que nous avons un échantillon représentatif et significatif et tout ce qu’il nous faut pour mesurer, de façon répétable et facile, chacun des changements que nous voulons effectuer, nous sommes en mesure de vérifier l’impact de 2 variables importantes : optimizer_search_depth et join_buffer_size.

Tout d’abord, la variable optimizer_search_depth dont voici les différents résultats :

Il est clair que cette variable a un impact majeur.  Nous savons maintenant que la valeur optimale de cette variable (dans notre cas précis) est 1.

On serait tenté de croire que la variable join_buffer_size pourrait avoir un impact non négligeable mais ce n’est pas le cas ici.

Les différences de temps (hormis pour la valeur 2Mb) ne sont pas assez significatives pour indiquer une tendance.  Malgré tout, théoriquement, cette variable devrait avoir un impact.  Pour les biens de la cause, autant avoir plus de mémoire que moins pour cette variable!  Je vous recommande donc 128Mb (plus, dans notre cas, serait un gaspillage de mémoire).

Finalement, pour mettre en valeur la différence entre une solution utilisant une table sur disque versus notre solution finale (une table en mémoire), l’histogramme suivant parle de lui-même!

Voilà!  CQFD. En espérant que cette série d’articles vous aura permis de constater que parfois, il est nécessaire de penser out of the box et d’envisager des solutions saugrenues pour arriver à ses fins.

7. Ressources et outils

Quelques-unes des ressources et des outils utilisés dans le cadre de cette série d’articles:

setbb.com : des forums de discussion sur le sudoku (en anglais) pour les programmeurs

enjoysudoku.com : des forums de discussions (en anglais) variés et nombreux sur les sudokus

QQWing : un outil (en ligne de commande) permettant de solutionner et de générer des grilles de sudoku

SudoCue : une application permettant de solutionner et générer des sudokus

Sudoku Explainer : une application permettant de solutionner et générer des sudokus

R : langage de programmation et environnement mathématique utilisé pour le traitement de données et l’analyse statistique

db4free.net : un serveur MySQL vous permettant de créer une base de donnée gratuitement et d’expérimenter

Pharo : un environnement de développement Smalltalk

## Une grosse surprise

12 avril 2013

Vous utilisez AVG AntiVirus et vous avez également installé AVG Toolbar dans votre fureteur préféré?

Sachez que le module AVG Toolbar, sans vous le dire, loggue une foule de renseignements sur les pages scannées et les connections effectuées à partir des pages web que vous consultez (principalement des publicités).  Ces informations sont sauvegardées dans un fichier nommé toolbar_log.txt qu’on retrouve habituellement dans le répertoire :

Documents and Settings\[NomDeLUsager]\Local Settings\Temp

Le hic c’est que ce fichier ne fait que grossir sans arrêt!  Quelle ne fut pas ma surprise de découvrir que celui-ci faisait 24 Gb sur ma machine!

Comment y remédier?  Fermez votre fureteur, supprimez le fichier pis redémarrez votre ordi.  Redémarrez votre fureteur puis fermez-le immédiatement.  Retrouvez le fichier toolbar_log.txt et changez ses propriétés pour le mettre read only.

Tada!  Fini les gigabytes de logs inutiles!

## Smalltalk et performance : tinyBenchmarks

8 décembre 2012

Il existe plusieurs programmes d’évaluation (benchmarks) servant à établir des comparaisons.  Le plus simple dont nous disposions en Smalltalk est tinyBenchmark (dans Squeak, Pharo et quelques autres saveurs de Smalltalk).

Ce petit test simpliste mesure le nombre de bytecodes traités par seconde ainsi que le nombre d’envois de messages (message sends) par seconde.  Bref, ce test vaut ce qu’il vaut : il évalue  principalement la rapidité de la machine virtuelle sans se soucier de l’efficacité et de la rapidité du code Smalltalk ou des primitives.

Un test plus représentatif et complet, comme le Computer Language Benchmark Game, est nettement plus révélateur de l’ensemble des capacité d’un environnement Smalltalk.  Dans le passé, il en existait des versions pour Squeak et GNU Smalltalk mais il ne semble maintenant rester que celle de VisualWorks.  Le code Smalltalk pour le CLBG est toutefois disponible ici

Malgré tout, par simple curiosité, j’ai utilisé tinyBenchmark pour comparer différentes versions de Smalltalk.  Les versions évaluées étaient:

• VisualWorks Non Commercial 7.8 (VW)
• ObjectStudio 7.1 (OS)
• VisualSmalltalk 3.0.1 (VS)
• Squeak 4.2 All-in-One (SQ)
• PharoCore 1.2 RC3 (PH)
• VA Smalltalk 7.5 (VAST)
• Dolphin Professional 6.02 (DP)
• Amber 0.9.1 (AM)

Sans m’en douter, quelques surprises m’attendaient!

1) Bytecodes par seconde

VisualWorks Non Commercial 7.8 : 607691685
ObjectStudio 7.1 : 35717175
Visual Smalltalk 3.0.1 : 281603053
Squeak 4.2 All-in-One : 85373820
PharoCore 1.2 RC3 : 97390689
VA Smalltalk 7.5 : 358381181
Dolphin Professional 6.02 : 110771676
Amber 0.9.1 : 2195520

Bytecodes par seconde

On remarque immédiatement la nette domination de VisualWorks sur tous ses concurrents et la seconde place de VisualAge.  La performance de VisualSmalltalk est surprenant tandis que je m’attendais à ce que Dolphin fasse mieux!  Évidemment, dans le cas d’Amber, il s’agit d’un petit nouveau mais laissons-lui le temps de mûrir un peu!

2) Envois de messages par seconde

VisualWorks Non Commercial 7.8 : 52403197
ObjectStudio 7.1 : 708240
VisualSmalltalk 3.0.1 : 59120053
Squeak 4.2 All-in-One : 3128033
Pharo Core 1.2 RC3 : 3828940
VA Smalltalk 7.5 : 19515614
Dolphin Professional 6.02 : 5097612
Amber 0.9.1 : 133367

Envois de messages par seconde

Grosse surprise ici!  VisualSmalltalk domine!  Évidemment, VisualWorks suit de près tandis que Dolphin me déçoit encore!  J’ai toujours eu l’impression que Dolphin était fichtrement rapide mais ce n’était, hélas, qu’une impression!

Évidemment, la liste des versions de Smalltalk est loin d’être complète. J’essaierai, un  de ces jours, de refaire ce petit test (ou mieux, le Computer Language Benchmark) pour tous les environnements mentionnés ci-haut ainsi que les versions de Smalltalk suivantes:

Bref, toute cette histoire ne fait que commencer!  J’essaierai d’aboutir avec une version de tinyBenchmark pour toutes les versions de Smalltalk mentionnées dans cet article et qui roulent sur Windows… Éventuellement, je ferai la même chose pour le Shootout Benchmark…

À suivre!

## Comment presser un citron (première partie)

7 janvier 2012

Ainsi donc, cette première partie détaillera la méthode de base utilisée pour résoudre un sudoku en une seule requête SQL.  Et en passant, pour ceux que la petite histoire intéresse, vous trouverez ici un excellent article sur l’évolution du sudoku.

Pour nous faciliter la tâche, nous utiliserons des tables de type MyISAM pour commencer.  Dans le prochain article, nous ferons aussi en sorte que notre méthode ne retourne qu’une seule grille valide même dans le cas où plusieurs solutions existeraient.  Rappelons que notre objectif ultime est d’optimiser une base de données dans le but bien précis de solutionner une grille valide dans des délais raisonnables.  Mais pour cet article, nous nous contenterons de verser dans la facilité!

Si l’envie vous prenait de vous salir les mains, vous aurez besoin d’un langage de programmation (idéalement Smalltalk comme j’utilise Pharo mais Squeak ou n’importe quel autre environnement Smalltalk fera l’affaire!) pour générer vous-même certaines données.  Si ce qui vous intéresse c’est seulement le résultat, n’importe quel client MySQL pourrait faire l’affaire comme je vous fournirai tous les scripts SQL nécessaires.

Ainsi, pour la suite de cet article, vous aurez besoin d’un client MySQL.

Bien que ce qui suit puisse se faire à l’aide de vos outils favoris, je vous suggère l’invite de commande et le client MySQL par souci de simplicité et de rapidité!

1. Création de la base de données

Il nous faut tout d’abord créer la base de données en exécutant:

```CREATE DATABASE sudoku;
```

2. Création de la table de positions

La solution (et la représentation des données que j’ai envisagée) pour résoudre ce problème est triviale : il s’agit de créer toutes les permutations possibles pour une ligne et de toutes les insérer dans une table que nous joindrons ensuite 9 fois sur elle-même de façon à créer le puzzle complet.  Évidemment,  nous devrons aussi ajouter toutes les règles nécessaires (dans une vue) pour que la grille soit valide ainsi que les valeurs de départ connues du sudoku.

Ainsi donc, comme la grille standard a 9 colonnes, il a fallu créer 9! (9 factorielle = 362880 = 9*8*7*6*5*4*3*2*1) lignes que nous avons insérées dans cette table.  Chaque enregistrement de la table positions représente une ligne de sudoku, constituée de ses 9 colonnes (de là les identifiants c1, c2, c3, c4, etc).

```USE sudoku;

CREATE TABLE positions (
c1 TINYINT UNSIGNED NOT NULL,
c2 TINYINT UNSIGNED NOT NULL,
c3 TINYINT UNSIGNED NOT NULL,
c4 TINYINT UNSIGNED NOT NULL,
c5 TINYINT UNSIGNED NOT NULL,
c6 TINYINT UNSIGNED NOT NULL,
c7 TINYINT UNSIGNED NOT NULL,
c8 TINYINT UNSIGNED NOT NULL,
c9 TINYINT UNSIGNED NOT NULL
) ENGINE=MYISAM;
```

Vous remarquerez l’absence d’index. Pour accélérer les choses, nous définirons les index seulement une fois la table remplie!  Les index seront essentiels dans notre cas, en particulier pour ce qui nous attend dans le prochain article!

3. Générer les données

J’ai créé les requêtes pour les INSERT dans la table positions à l’aide d’un petit script exécuté dans un workspace Pharo Smalltalk.

Voici le script utilisé :

```
| file |
file := StandardFileStream forceNewFileNamed: 'positions.sql'.
(1 to: 9) permutationsDo: [:e | file
nextPutAll: 'INSERT INTO positions(c1,c2,c3,c4,c5,c6,c7,c8,c9) VALUES(';
nextPutAll: (e at: 1) printString;nextPut: \$, ;
nextPutAll: (e at: 2) printString;nextPut: \$, ;
nextPutAll: (e at: 3) printString;nextPut: \$, ;
nextPutAll: (e at: 4) printString;nextPut: \$, ;
nextPutAll: (e at: 5) printString;nextPut: \$, ;
nextPutAll: (e at: 6) printString;nextPut: \$, ;
nextPutAll: (e at: 7) printString;nextPut: \$, ;
nextPutAll: (e at: 8) printString;nextPut: \$, ;
nextPutAll: (e at: 9) printString;nextPutAll: ');';cr].
file close.
```

Pour les plus aventuriers d’entre vous, je suggère d’étudier le contenu du fichier positions.sql afin de pouvoir générer l’équivalent à l’aide de votre langage de programmation favori! Pour les autres, j’ai déjà fait le travail et vous trouverez le fichier ici.

L’exécution de ce script dans un workspace créera un fichier nommé positions.sql  contenant toutes les requêtes de INSERT servant à remplir la table positions.

ATTENTION: la prochaine étape prend quelques minutes!

Pour insérer les données dans la table positions, ouvrez un invite de commande et exécutez ceci :

4. Générer les contraintes

Les contraintes de la requête servant à solutionner la grille sudoku ont aussi été générées à l’aide d’un script exécuté dans un workspace avec Pharo. Ce script élimine toute les clauses superflues ou dupliquées de façon à garder leur nombre au strict minimum en prenant bien soin de s’assurer d’avoir une grille de sudoku valide. Plus précisément, ce script veille à :

1) éliminer les clauses dupliquées (par exemple, nul besoin de spécifier que (r1.c3 <> r2.c3) et que (r2.c3 <> r1.c3), c’est la même chose!;

2) éliminer tous les clauses reliées aux lignes comme nous savons que toutes les lignes de la table position sont valides comme nous les avons toutes générées.

```| s1 s2 s3 |
s1 := Set new.
1 to: 9 do: [:r |
1 to: 9 do: [:c |    | cell |
cell := 'r', r printString, '.c', c printString.
1 to: 9 do: [:r2 |         | compCell |
compCell := 'r', r2 printString, '.c', c printString.
compCell ~= cell
ifTrue: [    cell < compCell
ifTrue: [s1 add: (cell, ' <> ', compCell)]
ifFalse: [s1 add: (compCell, ' <> ', cell)].
]
]
]
].
Transcript cr;show: '-- Unique in column';cr.
s1 asSortedCollection do: [:e | Transcript show: '(', e, ') AND ';cr].

s2 := Set new.
1 to: 9 do: [:r |
1 to: 9 do: [:c |    | cell deltaR deltaC |
deltaR := ((r-1) // 3) * 3.
deltaC := ((c-1) // 3) * 3.
1 to: 3 do: [:r2 |
1 to: 3 do: [:c2 |    | compCell |
cell := 'r', r printString, '.c', c printString.
compCell := 'r', (r2 + deltaR) printString, '.c', (c2 + deltaC) printString.
(compCell ~= cell and: [(r2 + deltaR) ~= r])
ifTrue:[    cell < compCell
ifTrue: [s2 add: (cell, ' <> ', compCell)]
ifFalse: [s2 add: (compCell, ' <> ', cell)].
]
]
]
]
].
Transcript cr;show: '-- Unique within 3x3 square';cr.
s3 := Set new.
s2 do: [:each | (s1 includes: each) ifFalse: [s3 add: each]].
s3 asSortedCollection do: [:e | Transcript show: '(', e, ') AND ';cr].
```

Nous utiliserons le résultat affiché dans le Transcript pour créer notre vue!

Note: il vous faudra préalablement changer une méthode dans Pharo pour être en mesure d’afficher la totalité des contraintes.

5. Créer les index

Pour accélérer la recherche, il nous faut des index! Il est temps de les générer!

ATTENTION: la prochaine étape prend plusieurs minutes!

```USE sudoku;

CREATE INDEX i12 ON positions(c1, c2); CREATE INDEX i13 ON positions(c1, c3);
CREATE INDEX i14 ON positions(c1, c4); CREATE INDEX i15 ON positions(c1, c5);
CREATE INDEX i16 ON positions(c1, c6); CREATE INDEX i17 ON positions(c1, c7);
CREATE INDEX i18 ON positions(c1, c8); CREATE INDEX i19 ON positions(c1, c9);
CREATE INDEX i23 ON positions(c2, c3); CREATE INDEX i24 ON positions(c2, c4);
CREATE INDEX i25 ON positions(c2, c5); CREATE INDEX i26 ON positions(c2, c6);
CREATE INDEX i27 ON positions(c2, c7); CREATE INDEX i28 ON positions(c2, c8);
CREATE INDEX i29 ON positions(c2, c9); CREATE INDEX i34 ON positions(c3, c4);
CREATE INDEX i35 ON positions(c3, c5); CREATE INDEX i36 ON positions(c3, c6);
CREATE INDEX i37 ON positions(c3, c7); CREATE INDEX i38 ON positions(c3, c8);
CREATE INDEX i39 ON positions(c3, c9); CREATE INDEX i45 ON positions(c4, c5);
CREATE INDEX i46 ON positions(c4, c6); CREATE INDEX i47 ON positions(c4, c7);
CREATE INDEX i48 ON positions(c4, c8); CREATE INDEX i49 ON positions(c4, c9);
CREATE INDEX i56 ON positions(c5, c6); CREATE INDEX i57 ON positions(c5, c7);
CREATE INDEX i58 ON positions(c5, c8); CREATE INDEX i59 ON positions(c5, c9);
CREATE INDEX i67 ON positions(c6, c7); CREATE INDEX i68 ON positions(c6, c8);
CREATE INDEX i69 ON positions(c6, c9); CREATE INDEX i78 ON positions(c7, c8);
CREATE INDEX i79 ON positions(c7, c9); CREATE INDEX i89 ON positions(c8, c9);
CREATE INDEX i9 ON positions(c9);
```

6. Créer une vue pour chercher les sudokus

C’est ici que les contraintes générées précédemment à l’aide de Pharo deviennent utiles!  Observez le nombre effarant de conditions dans la clause WHERE de la requête définissant la vue!

```USE sudoku;

CREATE VIEW sudoku_rows_view AS
SELECT
r1.c1 as r1c1, r1.c2 as r1c2, r1.c3 as r1c3, r1.c4 as r1c4, r1.c5 as r1c5, r1.c6 as r1c6, r1.c7 as r1c7, r1.c8 as r1c8, r1.c9 as r1c9, r2.c1 as r2c1,
r2.c2 as r2c2, r2.c3 as r2c3, r2.c4 as r2c4, r2.c5 as r2c5, r2.c6 as r2c6, r2.c7 as r2c7, r2.c8 as r2c8, r2.c9 as r2c9, r3.c1 as r3c1, r3.c2 as r3c2,
r3.c3 as r3c3, r3.c4 as r3c4, r3.c5 as r3c5, r3.c6 as r3c6, r3.c7 as r3c7, r3.c8 as r3c8, r3.c9 as r3c9, r4.c1 as r4c1, r4.c2 as r4c2, r4.c3 as r4c3,
r4.c4 as r4c4, r4.c5 as r4c5, r4.c6 as r4c6, r4.c7 as r4c7, r4.c8 as r4c8, r4.c9 as r4c9, r5.c1 as r5c1, r5.c2 as r5c2, r5.c3 as r5c3, r5.c4 as r5c4,
r5.c5 as r5c5, r5.c6 as r5c6, r5.c7 as r5c7, r5.c8 as r5c8, r5.c9 as r5c9, r6.c1 as r6c1, r6.c2 as r6c2, r6.c3 as r6c3, r6.c4 as r6c4, r6.c5 as r6c5,
r6.c6 as r6c6, r6.c7 as r6c7, r6.c8 as r6c8, r6.c9 as r6c9, r7.c1 as r7c1, r7.c2 as r7c2, r7.c3 as r7c3, r7.c4 as r7c4, r7.c5 as r7c5, r7.c6 as r7c6,
r7.c7 as r7c7, r7.c8 as r7c8, r7.c9 as r7c9, r8.c1 as r8c1, r8.c2 as r8c2, r8.c3 as r8c3, r8.c4 as r8c4, r8.c5 as r8c5, r8.c6 as r8c6, r8.c7 as r8c7,
r8.c8 as r8c8, r8.c9 as r8c9, r9.c1 as r9c1, r9.c2 as r9c2, r9.c3 as r9c3, r9.c4 as r9c4, r9.c5 as r9c5, r9.c6 as r9c6, r9.c7 as r9c7, r9.c8 as r9c8,
r9.c9 as r9c9

FROM
positions r1, positions r2, positions r3,
positions r4, positions r5, positions r6,
positions r7, positions r8, positions r9

WHERE
-- Nombres uniques dans chaque colonne
(r1.c1 <> r2.c1) AND (r1.c1 <> r3.c1) AND (r1.c1 <> r4.c1) AND (r1.c1 <> r5.c1) AND (r1.c1 <> r6.c1) AND (r1.c1 <> r7.c1) AND (r1.c1 <> r8.c1) AND (r1.c1 <> r9.c1) AND (r1.c2 <> r2.c2) AND (r1.c2 <> r3.c2) AND (r1.c2 <> r4.c2) AND (r1.c2 <> r5.c2) AND (r1.c2 <> r6.c2) AND (r1.c2 <> r7.c2) AND (r1.c2 <> r8.c2) AND (r1.c2 <> r9.c2) AND
(r1.c3 <> r2.c3) AND (r1.c3 <> r3.c3) AND (r1.c3 <> r4.c3) AND (r1.c3 <> r5.c3) AND (r1.c3 <> r6.c3) AND (r1.c3 <> r7.c3) AND (r1.c3 <> r8.c3) AND (r1.c3 <> r9.c3) AND (r1.c4 <> r2.c4) AND (r1.c4 <> r3.c4) AND (r1.c4 <> r4.c4) AND (r1.c4 <> r5.c4) AND (r1.c4 <> r6.c4) AND (r1.c4 <> r7.c4) AND (r1.c4 <> r8.c4) AND (r1.c4 <> r9.c4) AND
(r1.c5 <> r2.c5) AND (r1.c5 <> r3.c5) AND (r1.c5 <> r4.c5) AND (r1.c5 <> r5.c5) AND (r1.c5 <> r6.c5) AND (r1.c5 <> r7.c5) AND (r1.c5 <> r8.c5) AND (r1.c5 <> r9.c5) AND (r1.c6 <> r2.c6) AND (r1.c6 <> r3.c6) AND (r1.c6 <> r4.c6) AND (r1.c6 <> r5.c6) AND (r1.c6 <> r6.c6) AND (r1.c6 <> r7.c6) AND (r1.c6 <> r8.c6) AND (r1.c6 <> r9.c6) AND
(r1.c7 <> r2.c7) AND (r1.c7 <> r3.c7) AND (r1.c7 <> r4.c7) AND (r1.c7 <> r5.c7) AND (r1.c7 <> r6.c7) AND (r1.c7 <> r7.c7) AND (r1.c7 <> r8.c7) AND (r1.c7 <> r9.c7) AND (r1.c8 <> r2.c8) AND (r1.c8 <> r3.c8) AND (r1.c8 <> r4.c8) AND (r1.c8 <> r5.c8) AND (r1.c8 <> r6.c8) AND (r1.c8 <> r7.c8) AND (r1.c8 <> r8.c8) AND (r1.c8 <> r9.c8) AND
(r1.c9 <> r2.c9) AND (r1.c9 <> r3.c9) AND (r1.c9 <> r4.c9) AND (r1.c9 <> r5.c9) AND (r1.c9 <> r6.c9) AND (r1.c9 <> r7.c9) AND (r1.c9 <> r8.c9) AND (r1.c9 <> r9.c9) AND (r2.c1 <> r3.c1) AND (r2.c1 <> r4.c1) AND (r2.c1 <> r5.c1) AND (r2.c1 <> r6.c1) AND (r2.c1 <> r7.c1) AND (r2.c1 <> r8.c1) AND (r2.c1 <> r9.c1) AND (r2.c2 <> r3.c2) AND
(r2.c2 <> r4.c2) AND (r2.c2 <> r5.c2) AND (r2.c2 <> r6.c2) AND (r2.c2 <> r7.c2) AND (r2.c2 <> r8.c2) AND (r2.c2 <> r9.c2) AND (r2.c3 <> r3.c3) AND (r2.c3 <> r4.c3) AND (r2.c3 <> r5.c3) AND (r2.c3 <> r6.c3) AND (r2.c3 <> r7.c3) AND (r2.c3 <> r8.c3) AND (r2.c3 <> r9.c3) AND (r2.c4 <> r3.c4) AND (r2.c4 <> r4.c4) AND (r2.c4 <> r5.c4) AND
(r2.c4 <> r6.c4) AND (r2.c4 <> r7.c4) AND (r2.c4 <> r8.c4) AND (r2.c4 <> r9.c4) AND (r2.c5 <> r3.c5) AND (r2.c5 <> r4.c5) AND (r2.c5 <> r5.c5) AND (r2.c5 <> r6.c5) AND (r2.c5 <> r7.c5) AND (r2.c5 <> r8.c5) AND (r2.c5 <> r9.c5) AND (r2.c6 <> r3.c6) AND (r2.c6 <> r4.c6) AND (r2.c6 <> r5.c6) AND (r2.c6 <> r6.c6) AND (r2.c6 <> r7.c6) AND
(r2.c6 <> r8.c6) AND (r2.c6 <> r9.c6) AND (r2.c7 <> r3.c7) AND (r2.c7 <> r4.c7) AND (r2.c7 <> r5.c7) AND (r2.c7 <> r6.c7) AND (r2.c7 <> r7.c7) AND (r2.c7 <> r8.c7) AND (r2.c7 <> r9.c7) AND (r2.c8 <> r3.c8) AND (r2.c8 <> r4.c8) AND (r2.c8 <> r5.c8) AND (r2.c8 <> r6.c8) AND (r2.c8 <> r7.c8) AND (r2.c8 <> r8.c8) AND (r2.c8 <> r9.c8) AND
(r2.c9 <> r3.c9) AND (r2.c9 <> r4.c9) AND (r2.c9 <> r5.c9) AND (r2.c9 <> r6.c9) AND (r2.c9 <> r7.c9) AND (r2.c9 <> r8.c9) AND (r2.c9 <> r9.c9) AND (r3.c1 <> r4.c1) AND (r3.c1 <> r5.c1) AND (r3.c1 <> r6.c1) AND (r3.c1 <> r7.c1) AND (r3.c1 <> r8.c1) AND (r3.c1 <> r9.c1) AND (r3.c2 <> r4.c2) AND (r3.c2 <> r5.c2) AND (r3.c2 <> r6.c2) AND
(r3.c2 <> r7.c2) AND (r3.c2 <> r8.c2) AND (r3.c2 <> r9.c2) AND (r3.c3 <> r4.c3) AND (r3.c3 <> r5.c3) AND (r3.c3 <> r6.c3) AND (r3.c3 <> r7.c3) AND (r3.c3 <> r8.c3) AND (r3.c3 <> r9.c3) AND (r3.c4 <> r4.c4) AND (r3.c4 <> r5.c4) AND (r3.c4 <> r6.c4) AND (r3.c4 <> r7.c4) AND (r3.c4 <> r8.c4) AND (r3.c4 <> r9.c4) AND (r3.c5 <> r4.c5) AND
(r3.c5 <> r5.c5) AND (r3.c5 <> r6.c5) AND (r3.c5 <> r7.c5) AND (r3.c5 <> r8.c5) AND (r3.c5 <> r9.c5) AND (r3.c6 <> r4.c6) AND (r3.c6 <> r5.c6) AND (r3.c6 <> r6.c6) AND (r3.c6 <> r7.c6) AND (r3.c6 <> r8.c6) AND (r3.c6 <> r9.c6) AND (r3.c7 <> r4.c7) AND (r3.c7 <> r5.c7) AND (r3.c7 <> r6.c7) AND (r3.c7 <> r7.c7) AND (r3.c7 <> r8.c7) AND
(r3.c7 <> r9.c7) AND (r3.c8 <> r4.c8) AND (r3.c8 <> r5.c8) AND (r3.c8 <> r6.c8) AND (r3.c8 <> r7.c8) AND (r3.c8 <> r8.c8) AND (r3.c8 <> r9.c8) AND (r3.c9 <> r4.c9) AND (r3.c9 <> r5.c9) AND (r3.c9 <> r6.c9) AND (r3.c9 <> r7.c9) AND (r3.c9 <> r8.c9) AND (r3.c9 <> r9.c9) AND (r4.c1 <> r5.c1) AND (r4.c1 <> r6.c1) AND (r4.c1 <> r7.c1) AND
(r4.c1 <> r8.c1) AND (r4.c1 <> r9.c1) AND (r4.c2 <> r5.c2) AND (r4.c2 <> r6.c2) AND (r4.c2 <> r7.c2) AND (r4.c2 <> r8.c2) AND (r4.c2 <> r9.c2) AND (r4.c3 <> r5.c3) AND (r4.c3 <> r6.c3) AND (r4.c3 <> r7.c3) AND (r4.c3 <> r8.c3) AND (r4.c3 <> r9.c3) AND (r4.c4 <> r5.c4) AND (r4.c4 <> r6.c4) AND (r4.c4 <> r7.c4) AND (r4.c4 <> r8.c4) AND
(r4.c4 <> r9.c4) AND (r4.c5 <> r5.c5) AND (r4.c5 <> r6.c5) AND (r4.c5 <> r7.c5) AND (r4.c5 <> r8.c5) AND (r4.c5 <> r9.c5) AND (r4.c6 <> r5.c6) AND (r4.c6 <> r6.c6) AND (r4.c6 <> r7.c6) AND (r4.c6 <> r8.c6) AND (r4.c6 <> r9.c6) AND (r4.c7 <> r5.c7) AND (r4.c7 <> r6.c7) AND (r4.c7 <> r7.c7) AND (r4.c7 <> r8.c7) AND (r4.c7 <> r9.c7) AND
(r4.c8 <> r5.c8) AND (r4.c8 <> r6.c8) AND (r4.c8 <> r7.c8) AND (r4.c8 <> r8.c8) AND (r4.c8 <> r9.c8) AND (r4.c9 <> r5.c9) AND (r4.c9 <> r6.c9) AND (r4.c9 <> r7.c9) AND (r4.c9 <> r8.c9) AND (r4.c9 <> r9.c9) AND (r5.c1 <> r6.c1) AND (r5.c1 <> r7.c1) AND (r5.c1 <> r8.c1) AND (r5.c1 <> r9.c1) AND (r5.c2 <> r6.c2) AND (r5.c2 <> r7.c2) AND
(r5.c2 <> r8.c2) AND (r5.c2 <> r9.c2) AND (r5.c3 <> r6.c3) AND (r5.c3 <> r7.c3) AND (r5.c3 <> r8.c3) AND (r5.c3 <> r9.c3) AND (r5.c4 <> r6.c4) AND (r5.c4 <> r7.c4) AND (r5.c4 <> r8.c4) AND (r5.c4 <> r9.c4) AND (r5.c5 <> r6.c5) AND (r5.c5 <> r7.c5) AND (r5.c5 <> r8.c5) AND (r5.c5 <> r9.c5) AND (r5.c6 <> r6.c6) AND (r5.c6 <> r7.c6) AND
(r5.c6 <> r8.c6) AND (r5.c6 <> r9.c6) AND (r5.c7 <> r6.c7) AND (r5.c7 <> r7.c7) AND (r5.c7 <> r8.c7) AND (r5.c7 <> r9.c7) AND (r5.c8 <> r6.c8) AND (r5.c8 <> r7.c8) AND (r5.c8 <> r8.c8) AND (r5.c8 <> r9.c8) AND (r5.c9 <> r6.c9) AND (r5.c9 <> r7.c9) AND (r5.c9 <> r8.c9) AND (r5.c9 <> r9.c9) AND (r6.c1 <> r7.c1) AND (r6.c1 <> r8.c1) AND
(r6.c1 <> r9.c1) AND (r6.c2 <> r7.c2) AND (r6.c2 <> r8.c2) AND (r6.c2 <> r9.c2) AND (r6.c3 <> r7.c3) AND (r6.c3 <> r8.c3) AND (r6.c3 <> r9.c3) AND (r6.c4 <> r7.c4) AND (r6.c4 <> r8.c4) AND (r6.c4 <> r9.c4) AND (r6.c5 <> r7.c5) AND (r6.c5 <> r8.c5) AND (r6.c5 <> r9.c5) AND (r6.c6 <> r7.c6) AND (r6.c6 <> r8.c6) AND (r6.c6 <> r9.c6) AND
(r6.c7 <> r7.c7) AND (r6.c7 <> r8.c7) AND (r6.c7 <> r9.c7) AND (r6.c8 <> r7.c8) AND (r6.c8 <> r8.c8) AND (r6.c8 <> r9.c8) AND (r6.c9 <> r7.c9) AND (r6.c9 <> r8.c9) AND (r6.c9 <> r9.c9) AND (r7.c1 <> r8.c1) AND (r7.c1 <> r9.c1) AND (r7.c2 <> r8.c2) AND (r7.c2 <> r9.c2) AND (r7.c3 <> r8.c3) AND (r7.c3 <> r9.c3) AND (r7.c4 <> r8.c4) AND
(r7.c4 <> r9.c4) AND (r7.c5 <> r8.c5) AND (r7.c5 <> r9.c5) AND (r7.c6 <> r8.c6) AND (r7.c6 <> r9.c6) AND (r7.c7 <> r8.c7) AND (r7.c7 <> r9.c7) AND (r7.c8 <> r8.c8) AND (r7.c8 <> r9.c8) AND (r7.c9 <> r8.c9) AND (r7.c9 <> r9.c9) AND (r8.c1 <> r9.c1) AND (r8.c2 <> r9.c2) AND (r8.c3 <> r9.c3) AND (r8.c4 <> r9.c4) AND (r8.c5 <> r9.c5) AND
(r8.c6 <> r9.c6) AND (r8.c7 <> r9.c7) AND (r8.c8 <> r9.c8) AND (r8.c9 <> r9.c9) AND
-- Nombres uniques dans chaque maison de 3x3
(r1.c1 <> r2.c2) AND (r1.c1 <> r2.c3) AND (r1.c1 <> r3.c2) AND (r1.c1 <> r3.c3) AND (r1.c2 <> r2.c1) AND (r1.c2 <> r2.c3) AND (r1.c2 <> r3.c1) AND (r1.c2 <> r3.c3) AND (r1.c3 <> r2.c1) AND (r1.c3 <> r2.c2) AND (r1.c3 <> r3.c1) AND (r1.c3 <> r3.c2) AND (r1.c4 <> r2.c5) AND (r1.c4 <> r2.c6) AND (r1.c4 <> r3.c5) AND (r1.c4 <> r3.c6) AND
(r1.c5 <> r2.c4) AND (r1.c5 <> r2.c6) AND (r1.c5 <> r3.c4) AND (r1.c5 <> r3.c6) AND (r1.c6 <> r2.c4) AND (r1.c6 <> r2.c5) AND (r1.c6 <> r3.c4) AND (r1.c6 <> r3.c5) AND (r1.c7 <> r2.c8) AND (r1.c7 <> r2.c9) AND (r1.c7 <> r3.c8) AND (r1.c7 <> r3.c9) AND (r1.c8 <> r2.c7) AND (r1.c8 <> r2.c9) AND (r1.c8 <> r3.c7) AND (r1.c8 <> r3.c9) AND
(r1.c9 <> r2.c7) AND (r1.c9 <> r2.c8) AND (r1.c9 <> r3.c7) AND (r1.c9 <> r3.c8) AND (r2.c1 <> r3.c2) AND (r2.c1 <> r3.c3) AND (r2.c2 <> r3.c1) AND (r2.c2 <> r3.c3) AND (r2.c3 <> r3.c1) AND (r2.c3 <> r3.c2) AND (r2.c4 <> r3.c5) AND (r2.c4 <> r3.c6) AND (r2.c5 <> r3.c4) AND (r2.c5 <> r3.c6) AND (r2.c6 <> r3.c4) AND (r2.c6 <> r3.c5) AND
(r2.c7 <> r3.c8) AND (r2.c7 <> r3.c9) AND (r2.c8 <> r3.c7) AND (r2.c8 <> r3.c9) AND (r2.c9 <> r3.c7) AND (r2.c9 <> r3.c8) AND (r4.c1 <> r5.c2) AND (r4.c1 <> r5.c3) AND (r4.c1 <> r6.c2) AND (r4.c1 <> r6.c3) AND (r4.c2 <> r5.c1) AND (r4.c2 <> r5.c3) AND (r4.c2 <> r6.c1) AND (r4.c2 <> r6.c3) AND (r4.c3 <> r5.c1) AND (r4.c3 <> r5.c2) AND
(r4.c3 <> r6.c1) AND (r4.c3 <> r6.c2) AND (r4.c4 <> r5.c5) AND (r4.c4 <> r5.c6) AND (r4.c4 <> r6.c5) AND (r4.c4 <> r6.c6) AND (r4.c5 <> r5.c4) AND (r4.c5 <> r5.c6) AND (r4.c5 <> r6.c4) AND (r4.c5 <> r6.c6) AND (r4.c6 <> r5.c4) AND (r4.c6 <> r5.c5) AND (r4.c6 <> r6.c4) AND (r4.c6 <> r6.c5) AND (r4.c7 <> r5.c8) AND (r4.c7 <> r5.c9) AND
(r4.c7 <> r6.c8) AND (r4.c7 <> r6.c9) AND (r4.c8 <> r5.c7) AND (r4.c8 <> r5.c9) AND (r4.c8 <> r6.c7) AND (r4.c8 <> r6.c9) AND (r4.c9 <> r5.c7) AND (r4.c9 <> r5.c8) AND (r4.c9 <> r6.c7) AND (r4.c9 <> r6.c8) AND (r5.c1 <> r6.c2) AND (r5.c1 <> r6.c3) AND (r5.c2 <> r6.c1) AND (r5.c2 <> r6.c3) AND (r5.c3 <> r6.c1) AND (r5.c3 <> r6.c2) AND
(r5.c4 <> r6.c5) AND (r5.c4 <> r6.c6) AND (r5.c5 <> r6.c4) AND (r5.c5 <> r6.c6) AND (r5.c6 <> r6.c4) AND (r5.c6 <> r6.c5) AND (r5.c7 <> r6.c8) AND (r5.c7 <> r6.c9) AND (r5.c8 <> r6.c7) AND (r5.c8 <> r6.c9) AND (r5.c9 <> r6.c7) AND (r5.c9 <> r6.c8) AND (r7.c1 <> r8.c2) AND (r7.c1 <> r8.c3) AND (r7.c1 <> r9.c2) AND (r7.c1 <> r9.c3) AND
(r7.c2 <> r8.c1) AND (r7.c2 <> r8.c3) AND (r7.c2 <> r9.c1) AND (r7.c2 <> r9.c3) AND (r7.c3 <> r8.c1) AND (r7.c3 <> r8.c2) AND (r7.c3 <> r9.c1) AND (r7.c3 <> r9.c2) AND (r7.c4 <> r8.c5) AND (r7.c4 <> r8.c6) AND (r7.c4 <> r9.c5) AND (r7.c4 <> r9.c6) AND (r7.c5 <> r8.c4) AND (r7.c5 <> r8.c6) AND (r7.c5 <> r9.c4) AND (r7.c5 <> r9.c6) AND
(r7.c6 <> r8.c4) AND (r7.c6 <> r8.c5) AND (r7.c6 <> r9.c4) AND (r7.c6 <> r9.c5) AND (r7.c7 <> r8.c8) AND (r7.c7 <> r8.c9) AND (r7.c7 <> r9.c8) AND (r7.c7 <> r9.c9) AND (r7.c8 <> r8.c7) AND (r7.c8 <> r8.c9) AND (r7.c8 <> r9.c7) AND (r7.c8 <> r9.c9) AND (r7.c9 <> r8.c7) AND (r7.c9 <> r8.c8) AND (r7.c9 <> r9.c7) AND (r7.c9 <> r9.c8) AND
(r8.c1 <> r9.c2) AND (r8.c1 <> r9.c3) AND (r8.c2 <> r9.c1) AND (r8.c2 <> r9.c3) AND (r8.c3 <> r9.c1) AND (r8.c3 <> r9.c2) AND (r8.c4 <> r9.c5) AND (r8.c4 <> r9.c6) AND (r8.c5 <> r9.c4) AND (r8.c5 <> r9.c6) AND (r8.c6 <> r9.c4) AND (r8.c6 <> r9.c5) AND (r8.c7 <> r9.c8) AND (r8.c7 <> r9.c9) AND (r8.c8 <> r9.c7) AND (r8.c8 <> r9.c9) AND
(r8.c9 <> r9.c7) AND (r8.c9 <> r9.c8);
```

Maintenant, nous avons tout ce qu’il faut pour débuter! Si vous avez rencontré des difficultés avec le téléchargement du fichier positions.sql, contactez-moi et je me ferai un plaisir de vous envoyez le fichier compressé (format Gzip) par courriel. Consultez ma page « À propos » pour savoir à quelle adresse courriel me rejoindre!

7. Tester une grille

Asteure que toute la poutine (expression québécoise parfois utilisée pour désigner les tâches cléricales, répétitives, procédurales, techniques ou ennuyantes) est complétée, examinons comment notre solution se comporte pour cette grille :

Pour solutionner la grille, nous devons exécuter cette requête SQL :

```SELECT *
FROM sudoku_rows_view
WHERE
(r1c1 = 5) AND (r1c2 = 3) AND (r1c5 = 7) AND (r2c1 = 6) AND
(r2c4 = 1) AND (r2c5 = 9) AND (r2c6 = 5) AND (r3c2 = 9) AND
(r3c3 = 8) AND (r3c8 = 6) AND (r4c1 = 8) AND (r4c5 = 6) AND
(r4c9 = 3) AND (r5c1 = 4) AND (r5c4 = 8) AND (r5c6 = 3) AND
(r5c9 = 1) AND (r6c1 = 7) AND (r6c5 = 2) AND (r6c9 = 6) AND
(r7c2 = 6) AND (r7c7 = 2) AND (r7c8 = 8) AND (r8c4 = 4) AND
(r8c5 = 1) AND (r8c6 = 9) AND (r8c9 = 5) AND (r9c5 = 8) AND
(r9c8 = 7) AND (r9c9 = 9);```

Évidemment, je l’espère, vous aurez compris que r8c9 signifie « rangée 8 colonne 9 », etc.

Victoire!

Voici ce que le EXPLAIN de la requête a à dire :

```
mysql> explain
-> SELECT *
-> FROM sudoku_rows_view
-> WHERE
-> (r1c1 = 5) AND (r1c2 = 3) AND (r1c5 = 7) AND (r2c1 = 6) AND
-> (r2c4 = 1) AND (r2c5 = 9) AND (r2c6 = 5) AND (r3c2 = 9) AND
-> (r3c3 = 8) AND (r3c8 = 6) AND (r4c1 = 8) AND (r4c5 = 6) AND
-> (r4c9 = 3) AND (r5c1 = 4) AND (r5c4 = 8) AND (r5c6 = 3) AND
-> (r5c9 = 1) AND (r6c1 = 7) AND (r6c5 = 2) AND (r6c9 = 6) AND
-> (r7c2 = 6) AND (r7c7 = 2) AND (r7c8 = 8) AND (r8c4 = 4) AND
-> (r8c5 = 1) AND (r8c6 = 9) AND (r8c9 = 5) AND (r9c5 = 8) AND
-> (r9c8 = 7) AND (r9c9 = 9);
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+---------+------+------+--------------------------------------------------------------+
| id | select_type | table | type        | possible_keys                                                                                                                                      | key         | key_len | ref  | rows | Extra                                                        |
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+---------+------+------+--------------------------------------------------------------+
|  1 | SIMPLE      | r5    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i16,i19,i49 | 2,2,2   | NULL |   68 | Using intersect(i16,i19,i49); Using where                    |
|  1 | SIMPLE      | r2    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i14,i15,i16 | 2,2,2   | NULL |   78 | Using intersect(i14,i15,i16); Using where; Using join buffer |
|  1 | SIMPLE      | r8    | index_merge | i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9                                                                                     | i45,i46,i59 | 2,2,2   | NULL |   78 | Using intersect(i45,i46,i59); Using where; Using join buffer |
|  1 | SIMPLE      | r3    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i28,i38     | 2,2     | NULL |  551 | Using intersect(i28,i38); Using where; Using join buffer     |
|  1 | SIMPLE      | r6    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9                         | i19,i59     | 2,2     | NULL |  551 | Using intersect(i19,i59); Using where; Using join buffer     |
|  1 | SIMPLE      | r1    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i12,i15     | 2,2     | NULL |  624 | Using intersect(i12,i15); Using where; Using join buffer     |
|  1 | SIMPLE      | r9    | index_merge | i56,i57,i58,i59,i89,i9                                                                                                                             | i58,i59     | 2,2     | NULL |  624 | Using intersect(i58,i59); Using where; Using join buffer     |
|  1 | SIMPLE      | r4    | index_merge | i12,i13,i14,i15,i16,i17,i18,i19,i23,i24,i25,i26,i27,i28,i29,i34,i35,i36,i37,i38,i39,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9 | i15,i19     | 2,2     | NULL |  625 | Using intersect(i15,i19); Using where; Using join buffer     |
|  1 | SIMPLE      | r7    | index_merge | i23,i24,i25,i26,i27,i28,i29,i45,i46,i47,i48,i49,i56,i57,i58,i59,i67,i68,i69,i78,i79,i89,i9                                                         | i27,i28     | 2,2     | NULL |  625 | Using intersect(i27,i28); Using where; Using join buffer     |
+----+-------------+-------+-------------+----------------------------------------------------------------------------------------------------------------------------------------------------+-------------+---------+------+------+--------------------------------------------------------------+
9 rows in set (0.06 sec)

```

Voilà!

Tout fonctionne à merveille! Seulement 0.39 secondes pour solutionner la grille!  Savourons le résultat :

```
mysql> SELECT *
-> FROM sudoku_rows_view
-> WHERE
-> (r1c1 = 5) AND (r1c2 = 3) AND (r1c5 = 7) AND (r2c1 = 6) AND
-> (r2c4 = 1) AND (r2c5 = 9) AND (r2c6 = 5) AND (r3c2 = 9) AND
-> (r3c3 = 8) AND (r3c8 = 6) AND (r4c1 = 8) AND (r4c5 = 6) AND
-> (r4c9 = 3) AND (r5c1 = 4) AND (r5c4 = 8) AND (r5c6 = 3) AND
-> (r5c9 = 1) AND (r6c1 = 7) AND (r6c5 = 2) AND (r6c9 = 6) AND
-> (r7c2 = 6) AND (r7c7 = 2) AND (r7c8 = 8) AND (r8c4 = 4) AND
-> (r8c5 = 1) AND (r8c6 = 9) AND (r8c9 = 5) AND (r9c5 = 8) AND
-> (r9c8 = 7) AND (r9c9 = 9);
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
| r1c1 | r1c2 | r1c3 | r1c4 | r1c5 | r1c6 | r1c7 | r1c8 | r1c9 | r2c1 | r2c2 | r2c3 | r2c4 | r2c5 | r2c6 | r2c7 | r2c8 | r2c9 | r3c1 | r3c2 | r3c3 | r3c4 | r3c5 | r3c6 | r3c7 | r3c8 | r3c9 | r4c1 | r4c2 | r4c3 | r4c4 | r4c5 | r4c6 | r4c7 | r4c8 | r4c9 | r5c1 | r5c2 | r5c3 | r5c4 | r5c5 | r5c6 | r5c7 | r5c8 | r5c9 | r6c1 | r6c2 | r6c3 | r6c4 | r6c5 | r6c6 | r6c7 | r6c8 | r6c9 | r7c1 | r7c2 | r7c3 | r7c4 | r7c5 | r7c6 | r7c7 | r7c8 | r7c9 | r8c1 | r8c2 | r8c3 | r8c4 | r8c5 | r8c6 | r8c7 | r8c8 | r8c9 | r9c1 | r9c2 | r9c3 | r9c4 | r9c5 | r9c6 | r9c7 | r9c8 | r9c9 |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
|    5 |    3 |    4 |    6 |    7 |    8 |    9 |    1 |    2 |    6 |    7 |    2 |    1 |    9 |    5 |    3 |    4 |    8 |    1 |    9 |    8 |    3 |    4 |    2 |    5 |    6 |    7 |    8 |    5 |    9 |    7 |    6 |    1 |    4 |    2 |    3 |    4 |    2 |    6 |    8 |    5 |    3 |    7 |    9 |    1 |    7 |    1 |    3 |    9 |    2 |    4 |    8 |    5 |    6 |    9 |    6 |    1 |    5 |    3 |    7 |    2 |    8 |    4 |    2 |    8 |    7 |    4 |    1 |    9 |    6 |    3 |    5 |    3 |    4 |    5 |    2 |    8 |    6 |    1 |    7 |    9 |
+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+------+
1 row in set (0.39 sec)

```

Trop facile ? Hmmmm!?!? Peut-être!  À moins que…

C’était beaucoup trop beau! Comme nous le verrons au prochain article, plusieurs problèmes pointent à l’horizon (et espérons-le, plusieurs remèdes!) et nous devrons faire beaucoup mieux et plus vite avec les outils que nous avons pour arriver à résoudre certaines grilles très particulières.

En attendant la seconde partie de cet article, amusez-vous bien et expérimentez !

Note: j’ai déjà publié cet article en anglais sur mes autres blogues dont récemment ici (l’autre blogue est disparu depuis longtemps). Ne vous en faites pas, il ne s’agit pas d’un cas de plagiat!!!

Prochaine étape, chers lecteurs, nous apprendrons à presser un citron et à en extraire tout le jus!