Re: DB is slow until DB is reloaded

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



Gary Doades wrote:
From your queries it definitely looks like its your stats that are the problem. When the stats get well out of date the planner is choosing a hash join because it thinks thousands of rows are involved where as only a few are actually involved. Thats why, with better stats, the second query is using a loop join over very few rows and running much quicker.

Therefore it's ANALYZE you need to run as well as regular VACUUMing. There should be no need to VACUUM FULL at all as long as you VACUUM and ANALYZE regularly. Once a day may be enough, but you don't say how long it takes your database to become "slow".

You can VACUUM either the whole database (often easiest) or individual tables if you know in more detail what the problem is and that only certain tables need it.

Setting up autovacuum may well be sufficient.

Cheers,
Gary.

That explains things, thank you!

For the record; It was taking a few months for the performance to become intolerable. I've added CLUSTER -> ANALYZE -> VACUUM to my nightly routine and dropped the VACUUM FULL call. I'll see how this works.

Cheers!

Madi

--
Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-performance

[Postgresql General]     [Postgresql PHP]     [PHP Users]     [PHP Home]     [PHP on Windows]     [Kernel Newbies]     [PHP Classes]     [PHP Books]     [PHP Databases]     [Yosemite]

  Powered by Linux