Re: Very Poor Insert Performance

On Wednesday 29 October 2003 2:23 pm, Tom Lane wrote:

> Your initial message stated plainly that the problem was in INSERTs;
> it's not surprising that you got unhelpful advice.

But perhaps my use of the term "insert" to describe upload was a very bad call
given the domain of the list...

I assure you I wasn't setting out to deceive anyone! The only location i used
INSERT (ie as a Postgres keyword) was towards the end of my mail when I tried
to highlight the fact we couldn't use COPY to upload our data because of the
difficulty in maintaining the code to generate inter-table relations ahead of
time.

The problem was showing itself during database upload - so I assumed (ASS out
of U and ME and all that!) that the write delay was very large (hence the
disappointing improvements by switching off fsync etc). It was only after
further investigation that we discovered that simulated INSERTs were going
fine, but the Read delays between INSERTs where holding us up.

> Your LEFT JOINs are constraining the join order --- see
> http://www.postgresql.org/docs/7.3/static/explicit-joins.html
> You'll need to reorder the joins into something that does what you want.

Thanks very much for the heads-up, we'll reorder the joins into something more
effecient!

Damien