Re: Questions about 2 databases. - Mailing list pgsql-performance

From Tom Lane
Subject Re: Questions about 2 databases.
Date
Msg-id 5055.1110573222@sss.pgh.pa.us
Whole thread Raw
In response to Questions about 2 databases.  (jelle <jellej@pacbell.net>)
Responses Re: Questions about 2 databases.
List pgsql-performance
jelle <jellej@pacbell.net> writes:
> 1) on a single 7.4.6 postgres instance does each database have it own WAL
>     file or is that shared? Is it the same on 8.0.x?

Shared.

> 2) what's the high performance way of moving 200 rows between similar
>     tables on different databases? Does it matter if the databases are
>     on the same or seperate postgres instances?

COPY would be my recommendation.  For a no-programming-effort solution
you could just pipe the output of pg_dump --data-only -t mytable
into psql.  Not sure if it's worth developing a custom application to
replace that.

> My web app does lots of inserts that aren't read until a session is
> complete. The plan is to put the heavy insert session onto a ramdisk based
> pg-db and transfer the relevant data to the master pg-db upon session
> completion. Currently running 7.4.6.

Unless you have a large proportion of sessions that are abandoned and
hence never need be transferred to the main database at all, this seems
like a dead waste of effort :-(.  The work to put the data into the main
database isn't lessened at all; you've just added extra work to manage
the buffer database.

            regards, tom lane

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