Sunday, May 31, 2015

Fun with Bugs #36 - Bugs fixed in MySQL 5.6.25

Two days ago Oracle had released MySQL 5.6.25, so it's time to check what bugs reported by MySQL Community are fixed there. As usual, I'll mention both a bug reporter and engineer who verified the bug. Please, pay attention to fixes in replication and partitioning - if you use these features (or queries to INFORMATION_SCHEMA with a lot of complex tables in your database), please, consider upgrading ASAP.

The following InnoDB related bugs were fixed:
  • Bug #69990 - CREATE_TIME and UPDATE_TIME are wrong for partitioned tables. Finally this bug reported by my colleague Justin Swanhart and verified by Umesh (almost immediately after it was reported) is fixed!
  • Bug #75790 - memcached SET command accepts negative values for expire time. This bug (that Oracle put into InnoDB section in the release notes) was reported and verified by Umesh
  • Bug #74686  - Wrong relevance ranking for InnoDB full text searches under certain conditions. This bug was reported by Tim McLaughlin and verified by Miguel Solorzano.
  • The last but not the least, new innodb_stress test suite by Mark Callaghan is included now, thanks to the Bug #76347 reported by Viswanatham Gudipati.
Oracle had fixed several more memcached and InnoDB-related bugs in 5.6.25, but as they were reported only internally, they are out of the scope of my posts.

A set of related bugs in Partitioning category was fixed:
  • Bug #74288 - Assertion `part_share->partitions_share_refs->num_parts >= m_tot_parts' failed. It was reported by my colleague Roel Van de Paar and verified by Umesh.
  • Bug #74634 - this bug is still private, so we do not see the details.
  • Bug #74451 - this bug is also private. We can probably assume that in case of private bug we had assertion failures or crashes on non-debug builds. So, if you use partitioning a lot, please, consider upgrading to 5.6.25 ASAP.
A lot of replication related bugs were fixed in 5.6.25:
  • Bug #75879 - memory consumed quickly while executing loop in procedure. It was reported by Zhai Weixiang (who had also provided a patch) and verified by Shane Bester. If you ask me, based on the contributions over last 2 years it's about time for Percona to hire Zhai Weixiang into our development team, or Oracle may approach him faster. He is a really brilliant engineer!
  • Bug #75781 - log lock may not be unlocked if add_logged_gtid failed. It was reported by Fangxin Flou (who had provided a patch as well) and verified by Sinisa Milivojevic.
  • Bug #75769 - this bug is still private. Release notes describes the problem as follows: "A slave running MySQL 5.6.24 or earlier could not connect to a master running MySQL 5.7.6 and later that had gtid_mode=OFF_PERMISSIVE or gtid_mode=ON_PERMISSIVE." I wonder why such a bug can be private. Either it was reported like that or we do not see all the details about the impact.
  • Bug #75574 - Can not execute change master after Error occurred in MTS mode. It was reported by Zhang Yingqiang and verified by Sveta Smirnova (while she still worked in Oracle).
  • Bug #75570 - semi-sync replication performance degrades with a high number of threads. The problem was studied in details and reported by Rene' Cannao' and verified by Umesh.
  • Bug #74734  - mysqlbinlog can't decode events > ~1.6GB. It was reported by Hartmut Holzgraefe and verified by Umesh.
  • Bug #69848 - mysql 5.6 slave out of memory error. It was reported by  Jianjun Yang and verified by Sveta SmirnovaBug #72885 (where Shane Bester had clearly identified the memory leak)was declared a duplicate. If you use master-info-repository = TABLE on your 5.6.x slaves, please, consider upgrading to 5.6.25 ASAP.
  • Bug #70711 - mysqlbinlog prints invalid SQL from relay logs when GTID is enabled. This bug was reported by Yoshinori Matsunobu and probably verified formally by Luis Soares.
 There are several fixes in other categories:
  • Bug #75740 - Fix errors detected by ASan at runtime. It was reported and verified by Anitha Gopi based on request from WebScaleSQL team. 
  • Bug #76612 - would like ability to throttle firewall ACCESS DENIED messages in error log. This feature was requested by Shane Bester. Should I tell you again how much I am happy when I see public bug reports from Oracle employees?
  • Bug #76552 - Cannot shutdown MySQL using JDBC driver. This regression bug was reported by Davi Arnaut (who provided a patch as well) and verified by Umesh.
  • Bug #76019 is private. Release notes say: "Inappropriate -Werror options could appear in mysql_config --cflags output." Why on the Earth anyone could set or leave this bug as private is beyond my imagination.
  • Bug #74517 - thread/sql/main doesn't change state/info after startup. PERFORMANCE_SCHEMA was meant to be perfect already, but still some fixes are needed. The bug was reported by Kolbe Kegel and verified by Umesh.
  • Bug #72322 - Query to I_S.tables and I_S.columns leads to huge memory usage. Now I am impressed and I want to check the fix ASAP (as release notes do not say much)! If this bug (reported by my colleague Przemyslaw Malkowski just few weeks ago, on April 11, and verified by Umesh) is really fixed, it's a huge step forward in making INFORMATION_SCHEMA usable.
  • Bug #69638 - Wrong results when running a SELECT that includes a HAVING based on a function. The only optimizer bug from Community fixed in this version was reported by Roger Esteban and verified by Umesh.
  • Bug #69453 - Prepared statement is written to general query log after its execution is finish. It was reported by my colleague Sergei Glushchenko and verified by Umesh.
  • Bug #68999 - SSL_OP_NO_COMPRESSION not defined. It was reported by Remi Colletand verified probably by Georgi Kodinov.
To summarize, 24 or so bug reports from public bugs database were fixed in 5.6.25, of them fixes for replication, partitioned tables and INFORMATION_SCHEMA look really important and impressive. At least 10 of these bug reports were verified by Umesh. 4 bugs remain private, and I think it's probably wrong.

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