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Re: Large number of tables slow insert

From: tls(dot)wydd(at)free(dot)fr
To: Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>
Cc: DiezelMax <max(at)nts(dot)biz(dot)ua>, pgsql-performance(at)postgresql(dot)org
Subject: Re: Large number of tables slow insert
Date: 2008-08-24 00:09:13
Message-ID: 1219536553.48b0a6a9c6ea2@imp.free.fr (view raw or flat)
Thread:
Lists: pgsql-performance
On this smaller test, the indexes are over the allowed memory size (I've got
over 400.000 readings per sensor) so they are mostly written in disk. And on the
big test, I had small indexes (< page_size) because I only had about 5-10 rows
per table, thus it was 3000*8kb = 24mb which is lower than the allowed memory.

btw which is the conf parameter that contains the previously read indexes ?

I cannot do test this weekend because I do not have access to the machine but I
will try on monday some tests.

Thanks for your answers thought

Selon Scott Marlowe <scott(dot)marlowe(at)gmail(dot)com>:

> On Sat, Aug 23, 2008 at 1:35 PM,  <tls(dot)wydd(at)free(dot)fr> wrote:
> > Actually, I've got another test system with only few sensors (thus few
> tables)
> > and it's working well (<10ms insert) with all the indexes.
> > I know it's slowing down my performance but I need them to interogate the
> big
> > tables (each one can reach millions rows with time) really fast.
>
> It's quite likely that on the smaller system the indexes all fit into
> memory and only require writes, while on the bigger system they are
> too large and have to be read from disk first, then written out.
>
> A useful solution is to remove most of the indexes on the main server,
> and set up a slony slave with the extra indexes on it to handle the
> reporting queries.
>
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