On Thu, May 09, 2002 at 07:38:06PM -0400, Tom Lane wrote:
> =?iso-8859-1?Q?S=F8ren?= Boll Overgaard <postgres@fork.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.
Sorry, my bad.
Here is the real stuff:
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=75331.89..127823.94 rows=160293 width=24)
-> Seq Scan on hoststests ht (cost=0.00..49686.93 rows=160293 width=8)
-> Hash (cost=75243.51..75243.51 rows=35351 width=16)
-> Seq Scan on hostsqueue hq (cost=0.00..75243.51 rows=35351 width=16)
EXPLAIN
>
> 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.
After changing the enable_seqscan, the plan looks like this:
explain SELECT ht.id,hq.ip,hq.id FROM hostsqueue as hq,hoststests as ht WHERE ht.hostsqueue_id=hq.id;
NOTICE: QUERY PLAN:
Merge Join (cost=0.00..772324.63 rows=160293 width=24)
-> Index Scan using hostsqueue_pkey on hostsqueue hq (cost=0.00..137603.50 rows=35351 width=16)
-> Index Scan using idx_htsts_hq on hoststests ht (cost=0.00..632228.35 rows=160293 width=8)
EXPLAIN
As far as I can tell, that is excactly what we want. I will let the guys who
usually mess with the database have a go at it.
Thanks for the input so far, I really appreciate it.
--
Søren O. ,''`.
: :' :
public key: finger boll <at> db.debian.org `. `'
`-