Re: Query optimization

On Friday 04 Oct 2002 1:26 pm, Siva Kumar wrote:
> Giving below the output of EXPLAIN ANALYSE. I could not make much sense out
> of it, please help!

Scary aren't they ;-)

The important thing is you've got plenty of "Index Scan"s rather than Seq
Scans. The other point is the final time:

> Total runtime: 5.45 msec

Now, since that's not what you're getting, I'd think Neil (see other reply) is
right and you need to look at issuing "SET geqo = off;" before the query.

Postgresql has a genetic algorithm that kicks in on what it thinks is a very
complex query, this can take a long time to analyse the options available but
pays dividends on a big query. In your case you're only getting a few rows
and so it takes longer to analyse than to get the results.

The other thing that might work is rewriting the query with explicit JOINs - I
think that should make it clear to Postgresql what order to do things in.

- Richard Huxton