Thread: Using Explain

Using Explain

From

"P. Dwayne Miller"

Date:

05 July 2001, 11:29:33

After porting a database from FoxPro to PostgreSQL, one of the basic
queries that is used throughout the application now takes ~ 4 secs to
run, where it took ~ 40 usecs to run in FoxPro.  I've been trying to use
EXPLAIN to give me optimization hints, but I'm not sure what I'm looking
at.  Any places to look that might explain the results of explain?

Tks

Re: Using Explain

From

Tom Lane

Date:

05 July 2001, 12:22:42

"P. Dwayne Miller" <dmiller@espgroup.net> writes:
> Any places to look that might explain the results of explain?

http://www.ca.postgresql.org/users-lounge/docs/7.1/postgres/performance-tips.html

If you're still confused, feel free to post the query, table schemas,
and EXPLAIN output.

BTW, have you run VACUUM ANALYZE?  If not, you're unlikely to get a
good plan.
        regards, tom lane