Re: PG writes a lot to the disk - Mailing list pgsql-performance

From Gregory Stark
Subject Re: PG writes a lot to the disk
Date
Msg-id 87prtoqkdk.fsf@oxford.xeocode.com
Whole thread Raw
In response to Re: PG writes a lot to the disk  ("Laurent Raufaste" <analogue@glop.org>)
Responses Re: PG writes a lot to the disk  ("Laurent Raufaste" <analogue@glop.org>)
List pgsql-performance
"Laurent Raufaste" <analogue@glop.org> writes:

> All this make me think that PG was setting some bit on every row it
> used, which caused this massive write activity (3MB/s) in the table
> files. I'm talking about approx. 50 SELECT per second for a single
> server.

Well that's true it does. But only once per row. So analyze would have set the
bit on every row. You could do the same thing with something ligter like
"select count(*) from <table>".

Tom's thinking was that you would only expect a high update rate for a short
time until all those bits were set.

Slony's inserts, updates, and deletes count as updates to the table as well.

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  Gregory Stark
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