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#DBHangOps 11/13/13 -- MySQL setup through Puppet!

Here's the recording. Be sure to view the presentation and show notes below:

Hello everyone!

Participate in #DBHangOps this Wednesday, November 13th, 2013 at 12:00pm pacific (19:00 GMT), to hear about:

  • How do you ramp up new DBAs?
    • How do you ramp up a non-DBA to being a DBA?
  • How Mozilla manages MySQL through puppet
  • MySQL-isms!
    • (From Gerry) Sub SELECTs -- Why aren't these as mature as other databases?
    • (From Daniel) GROUP_CONCAT and other OLAP Style query functions -- Why doesn't MySQL have them?
    • (From Gerry) MySQL DBAs are used to building covering indexes to avoid PK lookups -- Is there a plan for this to change?

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 Wednesday!

See all of you on Wednesday!

Show notes

How Mozilla manages MySQL Through Pupppet

Feel free to fork the repository and submit fixes at on github at


  • The puppet module is focused on single-instance of mysql per host
    • Mozilla has additional glue that allows for multiple instances on backup servers
  • server ID is auto-generated from a custom script using the IP address
    • Mark Leith calls out this blog post that explains some pitfalls of adminstrators when setting server IDs
  • Only the needed YUM repositories should be realized for a given installation since there may be conflicts (e.g. MariaDB, Percona, Oracle, etc.)
  • Mozilla doesn't set swappiness to 0
    • The reason is so that the Out-of-Memory Killer (OOMKiller) doesn't kill MySQL on a host (since it's typically the largest memory consumer)
    • It's possible to exempt MySQL from the OOMKiller -- this way you could set swappiness to 0 and have other processes killed instead
    • If MySQL over-commits on memory, you may encounter a system crash.