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Bug #27531: the 4.1 fix.

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When checking for applicability of join cache
we must disable its usage only if there is no
temp table in use.
When a temp table is used we can use join
cache (and it will not make the result-set 
unordered) to fill the temp table. The filesort() 
operation is then applied to the data in the temp 
table and hence is not affected by join cache
usage.
Fixed by narrowing the condition for disabling 
join cache to exclude the case where temp table
is used.


mysql-test/r/join.result:
  Bug #27531: test case
mysql-test/t/join.test:
  Bug #27531: test case
sql/sql_select.cc:
  Bug #27531: 
  Disable join cache only if not using temp table
This commit is contained in:
unknown
2007-05-04 16:43:29 +03:00
parent 1a0e3a2858
commit 353b6f26b1
3 changed files with 80 additions and 3 deletions
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50
mysql-test/r/join.result
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@ -376,3 +376,53 @@ i i i
2 NULL 4
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drop table t1,t2,t3;
CREATE TABLE t1 (a int, b int default 0, c int default 1);
INSERT INTO t1 (a) VALUES (1),(2),(3),(4),(5),(6),(7),(8);
INSERT INTO t1 (a) SELECT a + 8 FROM t1;
INSERT INTO t1 (a) SELECT a + 16 FROM t1;
CREATE TABLE t2 (a int, d int, e int default 0);
INSERT INTO t2 (a, d) VALUES (1,1),(2,2),(3,3),(4,4);
INSERT INTO t2 (a, d) SELECT a+4, a+4 FROM t2;
INSERT INTO t2 (a, d) SELECT a+8, a+8 FROM t2;
EXPLAIN
SELECT STRAIGHT_JOIN t2.e FROM t1,t2 WHERE t2.d=1 AND t1.b=t2.e
ORDER BY t1.b, t1.c;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 ALL NULL NULL NULL NULL 32 Using temporary; Using filesort
1 SIMPLE t2 ALL NULL NULL NULL NULL 16 Using where
SELECT STRAIGHT_JOIN t2.e FROM t1,t2 WHERE t2.d=1 AND t1.b=t2.e
ORDER BY t1.b, t1.c;
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DROP TABLE t1,t2;