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Bug #48475: DISTINCT is ignored with GROUP BY WITH ROLLUP and

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only const tables

The problem was caused by two shortcuts in the optimizer that
are inapplicable in the ROLLUP case.

Normally in a case when only const tables are involved in a
query, DISTINCT clause can be safely optimized away since there
may be only one row produced by the join. Similarly, we don't
need to create a temporary table to resolve DISTINCT/GROUP
BY/ORDER BY. Both of these are inapplicable when the WITH
ROLLUP modifier is present.

Fixed by disabling the said optimizations for the WITH ROLLUP
case.

mysql-test/r/olap.result:
  Added a test case for bug #48475.
mysql-test/t/olap.test:
  Added a test case for bug #48475.
sql/sql_select.cc:
  Disabled const-only table optimizations for the WITH ROLLUP
  case.
This commit is contained in:
Alexey Kopytov
2009-11-06 09:44:01 +03:00
parent 43358bccd1
commit 39f9a3ffd0
3 changed files with 41 additions and 7 deletions
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12
mysql-test/r/olap.result
View File

@ -753,4 +753,16 @@ b
100
NULL
DROP TABLE t1, t2;
#
# Bug #48475: DISTINCT is ignored with GROUP BY WITH ROLLUP
# and only const tables
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b INT);
INSERT INTO t1 VALUES (1);
INSERT INTO t2 VALUES (1);
SELECT DISTINCT b FROM t1, t2 GROUP BY a, b WITH ROLLUP;
b
1
NULL
DROP TABLE t1, t2;
End of 5.0 tests

13
mysql-test/t/olap.test
View File

@ -390,4 +390,17 @@ SELECT DISTINCT b FROM t1, t2 GROUP BY a, b WITH ROLLUP;
DROP TABLE t1, t2;
--echo #
--echo # Bug #48475: DISTINCT is ignored with GROUP BY WITH ROLLUP
--echo # and only const tables
CREATE TABLE t1 (a INT);
CREATE TABLE t2 (b INT);
INSERT INTO t1 VALUES (1);
INSERT INTO t2 VALUES (1);
SELECT DISTINCT b FROM t1, t2 GROUP BY a, b WITH ROLLUP;
DROP TABLE t1, t2;
--echo End of 5.0 tests