To: Steve Eckmann <eckmann@computer.org>
cc: pgsql-performance@postgresql.org
Subject: Re: improving write performance for logging application 
In-reply-to: <43BB0C5C.8020207@computer.org> 
References: <43BB0C5C.8020207@computer.org>
Comments: In-reply-to Steve Eckmann <eckmann@computer.org>
	message dated "Tue, 03 Jan 2006 16:44:28 -0700"
Date: Tue, 03 Jan 2006 19:00:12 -0500
Message-ID: <27720.1136332812@sss.pgh.pa.us>
From: Tom Lane <tgl@sss.pgh.pa.us>

Steve Eckmann <eckmann@computer.org> writes:
> We also found that we could improve MySQL performance significantly
> using MySQL's "INSERT" command extension allowing multiple value-list
> tuples in a single command; the rate for MyISAM tables improved to
> about 2600 objects/second. PostgreSQL doesn't support that language
> extension. Using the COPY command instead of INSERT might help, but
> since rows are being generated on the fly, I don't see how to use COPY
> without running a separate process that reads rows from the
> application and uses COPY to write to the database.

Can you conveniently alter your application to batch INSERT commands
into transactions?  Ie

	BEGIN;
	INSERT ...;
	... maybe 100 or so inserts ...
	COMMIT;
	BEGIN;
	... lather, rinse, repeat ...

This cuts down the transactional overhead quite a bit.  A downside is
that you lose multiple rows if any INSERT fails, but then the same would
be true of multiple VALUES lists per INSERT.

			regards, tom lane