Re: pgstat: delayed write of stats file

Magnus Hagander wrote:
> Per some earlier discussion, here is an attempt at implementing a
> "delayed write" of the pgstats file, to decrease the write activity on
> that file.
>
> It changes so the file is only written once every 5 minutes (changeable
> of course, I just picked something) instead of once every half second.
> It's still written when the stats collector shuts down, just as before.
> And it is now also written on backend request. A backend requests a
> rewrite by simply sending a special stats message. It operates on the
> assumption that the backends aren't actually going to read the
> statistics file very often, compared to how frequent it's written today.

If somebody tries to read something from the pgstat file, is the backend
going to request a rewrite and wait until it is complete?

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Alvaro Herrera http://www.CommandPrompt.com/
The PostgreSQL Company - Command Prompt, Inc.