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MDEV-4817: Optimizer fails to optimize expression of the form 'FOO' IS NULL

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- Modify the way Item_cond::fix_fields() and Item_cond::eval_not_null_tables() 
  calculate bitmap for Item_cond_or::not_null_tables():
  if they see a "... OR inexpensive_const_false_item OR ..." then the item can
  be ignored.
- Updated test results. There can be more warnings produced since parts of WHERE 
  are evaluated more times.
This commit is contained in:
Sergey Petrunya
2013-07-31 17:24:52 +04:00
parent 6fb1786584
commit 04684b7709
10 changed files with 122 additions and 8 deletions
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2
mysql-test/r/subselect_cache.result
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@ -3129,6 +3129,7 @@ WHERE table1 .`col_varchar_key` ) field10
1 NULL f
Warnings:
Warning 1292 Truncated incorrect DOUBLE value: 'f'
Warning 1292 Truncated incorrect DOUBLE value: 'f'
SET @@optimizer_switch = 'subquery_cache=on';
/* cache is on */ SELECT COUNT( DISTINCT table2 .`col_int_key` ) , (
SELECT SUBQUERY2_t1 .`col_int_key`
@ -3144,6 +3145,7 @@ WHERE table1 .`col_varchar_key` ) field10
1 NULL f
Warnings:
Warning 1292 Truncated incorrect DOUBLE value: 'f'
Warning 1292 Truncated incorrect DOUBLE value: 'f'
drop table t1,t2,t3,t4;
set @@optimizer_switch= default;
#launchpad BUG#611625