Re: slow queries, possibly disk io - Mailing list pgsql-performance

From Josh Close
Subject Re: slow queries, possibly disk io
Date
Msg-id 4a0cafe205052705526fccfe75@mail.gmail.com
Whole thread Raw
In response to Re: slow queries, possibly disk io  (John Arbash Meinel <john@arbash-meinel.com>)
Responses Re: slow queries, possibly disk io
List pgsql-performance
> Setting shared buffers above something like 10-30% of memory is counter
> productive.

What is the reason behind it being counter productive? If shared
buffers are at 30%, should effective cache size be at 70%? How do
those two relate?

>
> Increasing sort_mem can help with various activities, but increasing it
> too much can cause you to swap, which kills performance. The caution is
> that you will likely use at least 1 sort_mem per connection, and can
> likely use more than one if the query is complicated.

I have a max of 100 connections and 2 gigs of mem. Right now the sort
mem is a 4 megs. How much higher could I put that?

-Josh

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