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Bug#47762: Incorrect result from MIN() when WHERE tests NOT

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NULL column for NULL

The optimization to read MIN() and MAX() values from an
index did not properly handle comparisons with NULL
values. Fixed by giving up the particular optimization step
if there are non-NULL safe comparisons with NULL values, as 
the result is NULL anyway.

Also, Oracle copyright notice was added to all files.
This commit is contained in:
Martin Hansson 2010-03-16 15:51:00 +01:00
commit 7cb796717e
5 changed files with 369 additions and 34 deletions
Download patch file Download diff file Expand all files Collapse all files

49
mysql-test/include/min_null_cond.inc Normal file
View file

@ -0,0 +1,49 @@
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = NULL;
SELECT MIN( a ) FROM t1 WHERE a = NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
SELECT MIN( a ) FROM t1 WHERE a <> NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a > NULL;
SELECT MIN( a ) FROM t1 WHERE a > NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a < NULL;
SELECT MIN( a ) FROM t1 WHERE a < NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
SELECT MIN( a ) FROM t1 WHERE a <=> NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND 10;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
SELECT MIN( a ) FROM t1 WHERE a BETWEEN NULL AND NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
SELECT MIN( a ) FROM t1 WHERE a BETWEEN 10 AND NULL;
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
SELECT MIN( a ) FROM t1 WHERE a = (SELECT a FROM t1 WHERE a < 0);
--replace_column 1 x 2 x 3 x 4 x 5 x 6 x 7 x 8 x 9 x
EXPLAIN
SELECT MIN( a ) FROM t1 WHERE a IS NULL;
SELECT MIN( a ) FROM t1 WHERE a IS NULL;