Friday, June 22

Tag: bloat

When autovacuum does not vacuum

2ndQuadrant, PostgreSQL, Tomas' PlanetPostgreSQL
A few weeks ago I explained basics of autovacuum tuning. At the end of that post I promised to look into problems with vacuuming soon. Well, it took a bit longer than I planned, but here we go. To quickly recap, autovacuum is a background process cleaning up dead rows, e.g. old deleted row versions. You can also perform the cleanup manually by running VACUUM, but autovacuum does that automatically depending on the amount of dead rows in the table, at the right moment - not too often but frequently enough to keep the amount of "garbage" under control. (more…)

Autovacuum Tuning Basics

2ndQuadrant, PostgreSQL, Tomas' PlanetPostgreSQL
A few weeks ago I covered the basics of tuning checkpoints, and in that post I also mentioned that the second common source of performance issues is autovacuum (based on what we see on the mailing list and at our customers under support). So let me follow-up on that with this post about the basics of autovacuum tuning. I'll very briefly explain the necessary theory (dead tuples, bloat and how autovacuum deals with it), but the main focus of this blog post is tuning - what configuration options are there, rules of thumb, etc. (more…)