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Fix for bug #34928: Confusion by having Primary Key and Index

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The bug is a regression introduced in 5.1 by the patch for bug28404.

Under some circumstances test_if_skip_sort_order() could leave some
data structures in an inconsistent state so that some parts of code
could assume the selected execution strategy for GROUP BY/DISTINCT as
a loose index scan (e.g. JOIN_TAB::is_using_loose_index_scan()), while
the actual strategy chosen was an ordered index scan, which led to
wrong data being returned.

Fixed test_if_skip_sort_order() so that when changing the type for a
join table, select->quick is reset not only for EXPLAIN, but for the 
actual join execution as well, to not confuse code that depends on its
value to determine the chosen GROUP BY/DISTINCT strategy.


mysql-test/r/distinct.result:
  Added a test case for bug #34928.
mysql-test/t/distinct.test:
  Added a test case for bug #34928.
sql/sql_select.cc:
  When changing the table's join type to JT_NEXT in 
  test_if_skip_sort_order(), also reset select->quick because other
  code may depend on its value to determine the GROUP BY/DISTINCT
  execution strategy.
This commit is contained in:
unknown
2008-03-26 19:37:36 +03:00
parent 92a09cf98b
commit b4b72fb306
3 changed files with 51 additions and 5 deletions
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23
mysql-test/r/distinct.result
View File

@ -682,3 +682,26 @@ a a b
1 1 3
DROP TABLE t1;
End of 5.0 tests
CREATE TABLE t1(a INT, b INT, c INT, d INT, e INT,
PRIMARY KEY(a,b,c,d,e),
KEY(a,b,d,c)
);
INSERT INTO t1(a, b, c) VALUES (1, 1, 1),
(1, 1, 2),
(1, 1, 3),
(1, 2, 1),
(1, 2, 2),
(1, 2, 3);
EXPLAIN SELECT DISTINCT a, b, d, c FROM t1;
id select_type table type possible_keys key key_len ref rows Extra
1 SIMPLE t1 index NULL a 16 NULL 6 Using index
SELECT DISTINCT a, b, d, c FROM t1;
a b d c
1 1 0 1
1 1 0 2
1 1 0 3
1 2 0 1
1 2 0 2
1 2 0 3
DROP TABLE t1;
End of 5.1 tests

23
mysql-test/t/distinct.test
View File

@ -553,3 +553,26 @@ SELECT DISTINCT a, a, b FROM t1;
DROP TABLE t1;
--echo End of 5.0 tests
#
# Bug #34928: Confusion by having Primary Key and Index
#
CREATE TABLE t1(a INT, b INT, c INT, d INT, e INT,
PRIMARY KEY(a,b,c,d,e),
KEY(a,b,d,c)
);
INSERT INTO t1(a, b, c) VALUES (1, 1, 1),
(1, 1, 2),
(1, 1, 3),
(1, 2, 1),
(1, 2, 2),
(1, 2, 3);
EXPLAIN SELECT DISTINCT a, b, d, c FROM t1;
SELECT DISTINCT a, b, d, c FROM t1;
DROP TABLE t1;
--echo End of 5.1 tests