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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 | 8e931fe53c55e203b285f30c892f24f106b56249 (patch) | |
| tree | 1b3100a0a72e06878015ac5a3ce9ed73dbd42b55 /mysql-test/t/range.test | |
| parent | 0e11bad589849ef5422dd5c4aca593ba01886dd8 (diff) | |
| download | mariadb-git-8e931fe53c55e203b285f30c892f24f106b56249.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.
Diffstat (limited to 'mysql-test/t/range.test')
| -rw-r--r-- | mysql-test/t/range.test | 11 |
1 files changed, 11 insertions, 0 deletions
diff --git a/mysql-test/t/range.test b/mysql-test/t/range.test index dc119b6a77e..f0fa99f3d95 100644 --- a/mysql-test/t/range.test +++ b/mysql-test/t/range.test @@ -1171,3 +1171,14 @@ a < 5 OR a < 10; DROP TABLE t1, t2, t3; + +--echo # +--echo # Bug #47123: Endless 100% CPU loop with STRAIGHT_JOIN +--echo # + +CREATE TABLE t1(a INT, KEY(a)); +INSERT INTO t1 VALUES (1), (NULL); +SELECT * FROM t1 WHERE a <> NULL and (a <> NULL or a <= NULL); +DROP TABLE t1; + +--echo End of 5.1 tests |