| From: | Pavel Stehule <pavel(dot)stehule(at)gmail(dot)com> |
|---|---|
| To: | AMatveev(at)bitec(dot)ru |
| Cc: | Achilleas Mantzios <achill(at)matrix(dot)gatewaynet(dot)com>, "pgsql-general(at)postgresql(dot)org >> PG-General Mailing List" <pgsql-general(at)postgresql(dot)org> |
| Subject: | Re: Memory usage per session |
| Date: | 2016-07-08 16:57:45 |
| Message-ID: | CAFj8pRAJDA+JxgMeCTwBsvUEop06WfZpO45DY9_64f0SbzHF6A@mail.gmail.com |
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| Lists: | pgsql-general |
2016-07-08 17:49 GMT+02:00 <AMatveev(at)bitec(dot)ru>:
> Hi
>
>
> >> Oracle: about 5M
> >> postgreSql: about 160М
>
>
>
> >The almost session memory is used for catalog caches. So you should to
> have big catalog and long living sessions.
>
> >What do you do exactly?
>
> I've generate test code that emulates instruction tree size for our
> production code.
> This test shows:
> -What is the size of instruction tree for our typical BP
> it's greater than 300M for each session
> -How often do PostgreSql parse the text
> When postgres clean cache, so much often
>
PostgreSQL parses the source code of functions once per session
>
>
> So Oracle is much better in this case.
> It's very difficult really estimate in such case, to buy Oracle or to by
> hardware.
>
Should be - The implementation of PLpgSQL and PL/SQL is strongly different.
When your case is not usual, then the migration to Postgres needs redesign
sometimes.
Regards
Pavel
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