Bug #47746 main.innodb_mysql fails sporadically
Submitted: 30 Sep 2009 13:27 Modified: 18 Dec 2009 23:45
Reporter: Alexander Nozdrin Email Updates:
Status: Closed Impact on me:
None 
Category:Tests: Engine Severity:S3 (Non-critical)
Version:5.1 OS:Any
Assigned to: John Embretsen CPU Architecture:Any
Tags: pb2, sporadic, test failure
Triage: Triaged: D3 (Medium)

[30 Sep 2009 13:27] Alexander Nozdrin
Description:
@@ -387,7 +387,7 @@
 DELETE FROM t1;
 EXPLAIN SELECT DISTINCT t1.name, t1.dept FROM t1 WHERE t1.name='rs5';
 id	select_type	table	type	possible_keys	key	key_len	ref	rows	Extra
-1	SIMPLE	t1	range	name	name	44	NULL	2	Using where; Using index for group-by
+1	SIMPLE	t1	range	name	name	44	NULL	1	Using where; Using index for group-by
 SELECT DISTINCT t1.name, t1.dept FROM t1 WHERE t1.name='rs5';
 name	dept
 DROP TABLE t1;

How to repeat:
http://pb2.norway.sun.com/web.py?template=mysql_show_test_failure&test_failure_id=2349440&...
[5 Oct 2009 12:21] John Embretsen
Based on triage comment and docs for EXPLAIN, I intend to propose a patch which masks the number in the 'rows' column of the EXPLAIN output following "DELETE FROM t1", as this number may vary between test runs.

Docs say:

<quote>
The rows column indicates the number of rows MySQL believes it must examine to execute the query. 

For InnoDB tables, this number is an estimate, and may not always be exact.
</quote>
http://dev.mysql.com/doc/refman/5.1/en/using-explain.html
[5 Oct 2009 13:16] Bugs System
A patch for this bug has been committed. After review, it may
be pushed to the relevant source trees for release in the next
version. You can access the patch from:

  http://lists.mysql.com/commits/85754

3156 John H. Embretsen	2009-10-05
      Bug#47746 - main.innodb_mysql fails sporadically:
      Mask part of EXPLAIN output with '#' to account for varying row count estimation.
     @ mysql-test/include/mix1.inc
        Mask 'rows' column in EXPLAIN output (number varies sometimes between 1 and 2).
     @ mysql-test/r/innodb_mysql.result
        Update result file after masking of rows estimation in EXPLAIN output.
[5 Oct 2009 13:54] Horst Hunger
Ready to push.
[6 Oct 2009 9:00] Bugs System
Pushed into 5.1.40 (revid:joro@sun.com-20091006073316-lea2cpijh9r6on7c) (version source revid:john.embretsen@sun.com-20091005131627-0r53yf3gwppwxlvm) (merge vers: 5.1.40) (pib:11)
[22 Oct 2009 6:36] Bugs System
Pushed into 6.0.14-alpha (revid:alik@sun.com-20091022063126-l0qzirh9xyhp0bpc) (version source revid:alik@sun.com-20091019135554-s1pvptt6i750lfhv) (merge vers: 6.0.14-alpha) (pib:13)
[22 Oct 2009 7:09] Bugs System
Pushed into 5.5.0-beta (revid:alik@sun.com-20091022060553-znkmxm0g0gm6ckvw) (version source revid:alik@sun.com-20091013094238-g67x6tgdm9a7uik0) (merge vers: 5.5.0-beta) (pib:13)
[28 Oct 2009 9:21] John Embretsen
This has been pushed and apparently merged to all relevant main branches, so I'm setting status to Documenting.
[28 Oct 2009 17:21] Paul Dubois
Test case changes. No changelog entry needed.
[18 Dec 2009 10:38] Bugs System
Pushed into 5.1.41-ndb-7.1.0 (revid:jonas@mysql.com-20091218102229-64tk47xonu3dv6r6) (version source revid:jonas@mysql.com-20091218095730-26gwjidfsdw45dto) (merge vers: 5.1.41-ndb-7.1.0) (pib:15)
[18 Dec 2009 10:54] Bugs System
Pushed into 5.1.41-ndb-6.2.19 (revid:jonas@mysql.com-20091218100224-vtzr0fahhsuhjsmt) (version source revid:jonas@mysql.com-20091217101452-qwzyaig50w74xmye) (merge vers: 5.1.41-ndb-6.2.19) (pib:15)
[18 Dec 2009 11:08] Bugs System
Pushed into 5.1.41-ndb-6.3.31 (revid:jonas@mysql.com-20091218100616-75d9tek96o6ob6k0) (version source revid:jonas@mysql.com-20091217154335-290no45qdins5bwo) (merge vers: 5.1.41-ndb-6.3.31) (pib:15)
[18 Dec 2009 11:23] Bugs System
Pushed into 5.1.41-ndb-7.0.11 (revid:jonas@mysql.com-20091218101303-ga32mrnr15jsa606) (version source revid:jonas@mysql.com-20091218064304-ezreonykd9f4kelk) (merge vers: 5.1.41-ndb-7.0.11) (pib:15)