Details
Description
Problem occurs on test table, which consists of two indexed comlumns and primary key column. With following query:
SELECT count(*) FROM `test` WHERE `col2` = '636146' AND `col1` = '7+';
result: 0
Same query while running after:
SET optimizer_switch='index_merge=off';
result: 73
I attach my test database, which is derived from production database where issue occurs. I was able to reproduce problem on several other systems.
I was unable to reproduce same error on MySQL 5.5.35
Issue might be related to "intersect(col1,col2);" in query EXPLAIN, while any modification of query (eg. adding OR condition to WHERE expression) seems to avoid the issue. Deleting primary key (which is not involved in query), changing table to MyISAM seems to cause correct behavior of system.
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Issue Links
- relates to
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MDEV-5177 ha_partition and innodb index intersection produce fewer rows (MySQL Bug#70703)
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- Closed
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Elena, is it reproducible on MySQL 5.6.16 or on MySQL 5.6.15?
I'm using the top of the public mysql-server/5.6 bzr tree, which has revno 5732 (tag mysql-5.6.16), dated 2014-01-09.
Vojtech, thanks for taking time to report the issue. Although this one has turned out to be already known, we (MariaDB devs) appreciate getting input.
Thank you for fix. I'll be waiting for next release. In meantime I'll use 'index_merge=off' as workaround.
Reproducible with the data from the attachment and the query from the description: on 5.3 (14/73 rows), 5.5, 10.0 (0/73 rows), mysql-5.6 (70/73 rows).
The bug is likely to be a duplicate of
MDEV-5177, but since the latter turned out to be tricky, I suggest to make sure the bugfix covers this test case as well before closing it.