database/mariadb
1
0
Fork 0
mirror of https://github.com/MariaDB/server.git synced 2025-08-01 03:47:19 +03:00
Code Activity

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

Browse Source 
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
Download Patch File Download Diff File Expand all files Collapse all files

23
mysql-test/r/distinct.result
View File

@ -682,3 +682,26 @@ a a b
1 1 3 1 1 3
DROP TABLE t1; DROP TABLE t1;
End of 5.0 tests 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; DROP TABLE t1;
--echo End of 5.0 tests --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

10
sql/sql_select.cc
View File

@ -13158,6 +13158,11 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
tab->read_first_record= best_key_direction > 0 ? tab->read_first_record= best_key_direction > 0 ?
join_read_first:join_read_last; join_read_first:join_read_last;
tab->type=JT_NEXT; // Read with index_first(), index_next() tab->type=JT_NEXT; // Read with index_first(), index_next()
if (select && select->quick)
{
delete select->quick;
select->quick= 0;
}
if (table->covering_keys.is_set(best_key)) if (table->covering_keys.is_set(best_key))
{ {
table->key_read=1; table->key_read=1;
@ -13168,11 +13173,6 @@ test_if_skip_sort_order(JOIN_TAB *tab,ORDER *order,ha_rows select_limit,
{ {
tab->ref.key= -1; tab->ref.key= -1;
tab->ref.key_parts= 0; tab->ref.key_parts= 0;
if (select && select->quick)
{
delete select->quick;
select->quick= 0;
}
if (select_limit < table_records) if (select_limit < table_records)
tab->limit= select_limit; tab->limit= select_limit;
} }