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[Bug 1007027] Re: Unnecessary "SELECT 1" statements spamming MySQL server

To: yahoo-eng-team@xxxxxxxxxxxxxxxxxxx
From: Sean Dague <sean@xxxxxxxxx>
Date: Mon, 15 Sep 2014 12:00:22 -0000
Reply-to: Bug 1007027 <1007027@xxxxxxxxxxxxxxxxxx>
Sender: bounces@xxxxxxxxxxxxx

All this code is out of nova now, removing it

** No longer affects: nova

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https://bugs.launchpad.net/bugs/1007027

Title:
  Unnecessary "SELECT 1" statements spamming MySQL server

Status in Oslo Database library:
  Incomplete

Bug description:
  Nova is issuing a lot of unnecessary "SELECT 1" queries against its
  MySQL database. I believe this is due to the MySQLPingListener()
  function in nova/db/sqlalchemy/session.py.

  Even though "SELECT 1" is a light-weight database call, it is
  unnecessary and wasting resources (database CPU cycles) and time
  (extra network round trips), and is not guaranteeing a valid database
  connection. In other words, it is just a waste of resources.

  See http://www.mysqlperformanceblog.com/2010/05/05/checking-for-a
  -live-database-connection-considered-harmful/ for a longer discussion
  of why this should be removed.

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