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| author | Alexey Kopytov <Alexey.Kopytov@Sun.com> | 2009-10-17 00:19:51 +0400 |
|---|---|---|
| committer | Alexey Kopytov <Alexey.Kopytov@Sun.com> | 2009-10-17 00:19:51 +0400 |
| commit | f6868a4eb42f39a5f4e8179b91fe38f0ff299ebe (patch) | |
| tree | 1b3100a0a72e06878015ac5a3ce9ed73dbd42b55 /mysql-test/r/subselect.result | |
| parent | e066294824b2319ca1c27ea2cc38ad2e8d1b8b3e (diff) | |
| download | mariadb-git-f6868a4eb42f39a5f4e8179b91fe38f0ff299ebe.tar.gz | |
Bug #47123: Endless 100% CPU loop with STRAIGHT_JOIN
The problem was in incorrect handling of predicates involving
NULL as a constant value by the range optimizer.
For example, when creating a SEL_ARG node from a condition of
the form "field < const" (which would normally result in the
"NULL < field < const" SEL_ARG), the special case when "const"
is NULL was not taken into account, so "NULL < field < NULL"
was produced for the "field < NULL" condition.
As a result, SEL_ARG structures of this form could not be
further optimized which in turn could lead to incorrectly
constructed SEL_ARG trees. In particular, code assuming SEL_ARG
structures to always form a sequence of ordered disjoint
intervals could enter an infinite loop under some
circumstances.
Fixed by changing get_mm_leaf() so that for any sargable
predicate except "<=>" involving NULL as a constant, "empty"
SEL_ARG is returned, since such a predicate is always false.
mysql-test/r/partition_pruning.result:
Fixed a broken test case.
mysql-test/r/range.result:
Added a test case for bug #47123.
mysql-test/r/subselect.result:
Fixed a broken test cases.
mysql-test/t/range.test:
Added a test case for bug #47123.
sql/opt_range.cc:
Fixed get_mm_leaf() so that for any sargable
predicate except "<=>" involving NULL as a constant, "empty"
SEL_ARG is returned, since such a predicate is always false.
Diffstat (limited to 'mysql-test/r/subselect.result')
| -rw-r--r-- | mysql-test/r/subselect.result | 3 |
1 files changed, 1 insertions, 2 deletions
diff --git a/mysql-test/r/subselect.result b/mysql-test/r/subselect.result index c60ac9790c5..788abbd2577 100644 --- a/mysql-test/r/subselect.result +++ b/mysql-test/r/subselect.result @@ -4403,8 +4403,7 @@ FROM t1 WHERE a = 230; id select_type table type possible_keys key key_len ref rows Extra 1 PRIMARY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables -2 DEPENDENT SUBQUERY st1 index NULL a 5 NULL 2 Using index -2 DEPENDENT SUBQUERY st2 index b b 5 NULL 2 Using where; Using index; Using join buffer +2 DEPENDENT SUBQUERY NULL NULL NULL NULL NULL NULL NULL Impossible WHERE noticed after reading const tables SELECT MAX(b), (SELECT COUNT(*) FROM st1,st2 WHERE st2.b <= t1.b) FROM t1 WHERE a = 230; |