Re: trouble with (lack of) indexing

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Søren Boll Overgaard <postgres(at)fork(dot)dk>
Cc: Scott Marlowe <scott(dot)marlowe(at)ihs(dot)com>, pgsql-general(at)postgresql(dot)org
Subject: Re: trouble with (lack of) indexing
Date: 2002-05-09 23:38:06
Message-ID: 24348.1020987486@sss.pgh.pa.us
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=?iso-8859-1?Q?S=F8ren?= Boll Overgaard <postgres(at)fork(dot)dk> writes:
> explain SELECT ht.id,hq.ip,hq.id FROM
> hostsqueue as hq,hoststests as ht WHERE ht.hostsqueue_id=hq.id;
> NOTICE: QUERY PLAN:

> Hash Join (cost=776.05..2904.36 rows=84 width=24)
> -> Seq Scan on hoststests ht (cost=0.00..2126.84 rows=84 width=8)
> -> Hash (cost=776.04..776.04 rows=4 width=16)
> -> Seq Scan on hostsqueue hq (cost=0.00..776.04 rows=4 width=16)

If there's only 84 rows it's hardly going to matter which plan we choose
;-). Please show us the results from the production database, not the
toy-sized tables.

If you have 7.2 then EXPLAIN ANALYZE is much more useful to show than
plain EXPLAIN. Also, you could try doing "SET enable_seqscan = off"
and see how the plan changes.

regards, tom lane

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