Sleeping connections

Why is it so important to close connections to databases if there’s no explicit need to keep them open (which usually the case)?

Symptoms

  • Icinga reports high usage of allowed connections (>90%) on master MySQL server.
  • No running queries or any specific in processlist. All the connections are sleeping … Continue reading

Unindexed queries can be really expensive

computer-key-money-box

The story happened with a webshop application running on Amazon EC2 microinstances. Actually on two instance. Amazon business model is basically simple, they ask money for only three things: Cpu time, IOPS and network traffic. Everybody (including me) thinks for the first time network traffic will be the bottleneck until … Continue reading