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#DBHangOps 08/21/14 -- GTIDs, Shared Storage, and more!

You can watch the recording below:

Hello everybody!

Join in #DBHangOps this Thursday, August, 21, 2014 at 11:00am pacific (18:00 GMT), to participate in the discussion about:

  • GTIDs in MariaDB Demo from Gerry!
  • Shared storage and MySQL
    • How about NFS?
  • Index Fragmentation (requested by Shlomi)

Be sure to check out the #DBHangOps twitter search, the @DBHangOps twitter feed, or this blog post to get a link for the google hangout on Thursday!

See all of you on Thursday!

Show notes

GTIDs in MariaDB

  • MariaDB is always implicitly running with GTIDs under the hood, even if you don't have them enabled.
    • This allows you to easily enable/disable GTIDs on a running server without shutting down a whole topology of machines
    • You can convert a master's binlog coordinates to GTID coordinates using "SELECT BINLOG_GTID_POS('binlog_file.000001', binlog_pos)"
      • This is similar to doing "MASTER_AUTO_POSITION" in Oracle MySQL.
  • Future version of MySQL 5.7 will begin allowing for enabling GTIDs without restarting MySQL
  • MySQL creates a UUID to identify itself for GTIDs whereas MariaDB depends on the setting of server_id
    • If you want stronger uniqueness for server_id, you can use the "inet_aton()" function in MySQL to create a numerical representation of an IP address

Shared storage and NFS

  • A lot of the historical issues with NFS have improved with NFSv4 since there is now mandatory and advisory locking support
  • The "binlog_impossible_mode" variable is extremely useful to set for MySQL servers running on NFS
  • A word of caution: historically, periodic performance issues with a database server could be as a result of shared storage if it's used by other machines
  • Also be cognizant of NFS issues and documentation with mysql -- http://bugs.mysql.com/bug.php?id=71969
  • Would shared storage be better going forward now that we can start using SSDs in shared storage devices?
  • Ideally, putting less-performance-critical data onto NFS would allow you to leverage the best of both worlds
    • There's an option to store individual tables on different data directories in future versions of MySQL?