Saturday, May 31, 2014

Fun with Bugs #33 - bugs fixed in MySQL 5.6.19

It seems Oracle released MySQL 5.6.19 yesterday. So, it's time to check what community bug reports are fixed there.

Let's start with InnoDB. We have the following bugs fixed:
  • Bug #72079, "Upgrade from 5.6.10 to 5.6.16 crashes and leaves unusable DB". Honestly I had not noted this bug, even though I upgrade several instances on Windows to each and every release since 5.6.8. Probably because I had no need to use FTS indexes till recently...
  • Bug #71014, about two extra memset calls that are now removed. I hope the patch bug report provided was just used.
  • Bug #69641, "Crash when enabling innodb_table_monitor (assertion: ib_table->stat_initialized)". Good to see one more crash fixed.
  • Bug #62534, "off by one error in innodb_max_dirty_pages_pct logic". Reported by Domas and fixed by Facebook long time ago. But it seems current fix from Oracle is somewhat more complex than just replacing ">" with ">="... Maybe my comment about Informix having decimal (instead of integer) as a data type for similar variable helped :)
The following replication bugs are fixed in 5.6.19:
  • Bug #71070, "kill of truncate table will lead to binary log written while rows remains". I am really happy to this it fixed finally!
  • Bug #71376, "restart of slave instance fail in GTID replication if we use replicate-ignore-db". Also great to see this fixed. Note that to add more confusion, Bug #71326 is mentioned instead as replication bug that is fixed, but this is actually a MySQL Workbench bug. I tried to guess what other community bug it could really be, and ended up with this one. Let's home release notes will be fixed soon accordingly.
  • Bug #71179, "CREATE TABLE .. SELECT produces invalid structure, breaks RBR". Replication is just one of the areas affected though. Let me quote details of the fix (added by Laurynas Biveinis, he does this for each and every community bug fixed. I wonder why Oracle does NOT care to do that themselves?):

      This fix changes the DIV operation implementation to correctly
      evaluate the display width of its result. We check if DIV's
      results estimated width crosses maximum width for integer
      value (21) and if yes set it to this maximum value.
  • Bug #70891 is also listed as fixed, but it is still private, so we can only guess what exactly it was about or just trust release notes... 
 On top of that, few old bugs from other categories were also fixed:
  • Bug #66803, "Allow compilation using Clang in C++11 mode". Clang is becoming popular. Still not sure why it took so much time to fix the problem when original bug report had a patch.
  • Bug #71089, "CMake warning when generating Makefile". No more warning for new CMake versions.
  • Bug #51840, "infinite hang with 100% cpu usage with load data local and import errors". Reported by Shane more than 4 years ago, it was fixed only in 5.6.19. This fix may be the only really good reason to upgrade to 5.6.19, by the way!
  • Bug #69683, "Optimize after a delete returns error 0 can't get stat of MYD file". Actually, it was a problem for MyISAM tables with .MYD files larger than 4GB on Windows. If you care about Windows and MyISAM (really?), then you have one more good reason to upgrade.
  • Bug #69684, "The update and select behave differently under the same conditions". Probably the only fix from the Optimizer team in this release.
That's all, folks! Just 13 community bugs fixed over 2 months, according to the official Release Notes (that has a bug...). I am not impressed and I see a reason to upgrade only if you care about top INSERT performance for InnoDB, or if you use GTID and/or row-based replication setup, or may get LOAD DATA LOCAL statements for files with uncontrolled content. Other fixed are for some rare/corner cases or compilation problems, and I'd happily wait for 5.6.20 to fix some more bugs I so much care about...

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