Re: Postgres 9.1.4 - high stats collector IO usage

2012/8/6 Magnus Hagander <magnus(at)hagander(dot)net>:
> On Mon, Aug 6, 2012 at 4:16 PM, Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> wrote:
>> 2012/8/6 Magnus Hagander <magnus(at)hagander(dot)net>:
>>> That's not a good way of doing it, since you loose persistent storage.
>>>
>>> Instead, you should set the stats_temp_dir paramter to a filesystem
>>> somewhere else that is tmpfs. Then PostgreSQL will automatically move
>>> the file to and from the main data directory on startup and shutdown,
>>> so you get both the performance of tmpfs and the persistent
>>> statistics.
>>
>> we had to do it because our read/write of stat file created really
>> high IO - and it was problem on Amazon :( - probably we had not this
>> issue elsewhere
>
> Uh. You realize that if you set stats_temp_dir, it only ever writes to
> the persistent storage once, when you do "pg_ctl stop" (or
> equivalent). Are you saying the shutdown took too long?
>
> I've had to change that param many times on Amazon, but I've never had
> a problem with the shutdown writes. (And I've seen it often enough on
> dedicated hardware as well..)
aha, this is my mistake - we use a stats_temp_directory GUC already -
my advice was use a tmpfs for statfile, but I though realize it via
stats_temp_directory, but I didn't say it.

Regards

Pavel

>
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> Magnus Hagander
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