From: Tomasz Myrta <jasiek@klaster.net>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Lista dyskusyjna pgsql-sql <pgsql-sql@postgresql.org>
Subject: Re: explicit joins wrong planning
Date: Fri, 28 Nov 2003 20:43:33 +0100
Message-ID: <3FC7A565.4000104@klaster.net> (raw)
In-Reply-To: <29784.1070047126@sss.pgh.pa.us>
References: <3FC63057.3080009@klaster.net>
<29784.1070047126@sss.pgh.pa.us>
Dnia 2003-11-28 20:18, Użytkownik Tom Lane napisał:
> Hard to say much when you didn't actually show us the output of EXPLAIN
> ANALYZE.
OK, Here you are:
explain analyze select *
from plany pl
join linia_trasy lt using (id_linii)
join kursy k on (k.id_trasy=lt.id_trasy and
k.event_date=pl.begindate+lt.offset)
where pl.id_planu=508;
event_date - date
begindate - date
id_linii - integer
id_trasy - integer
offset - integer
QUERY PLAN
--------------------------------------------------------------------------------------------------------------------------------------
Hash Join (cost=5.82..1210.68 rows=2 width=40) (actual
time=718.11..759.27 rows=5 loops=1)
Hash Cond: ("outer".id_trasy = "inner".id_trasy)
Join Filter: ("outer".event_date = ("inner".begindate + "inner".offset))
-> Seq Scan on kursy k (cost=0.00..876.07 rows=58707 width=11)
(actual time=0.02..547.65 rows=58707 loops=1)
-> Hash (cost=5.81..5.81 rows=7 width=29) (actual time=0.43..0.43
rows=0 loops=1)
-> Nested Loop (cost=0.00..5.81 rows=7 width=29) (actual
time=0.16..0.37 rows=7 loops=1)
Join Filter: ("outer".id_linii = "inner".id_linii)
-> Index Scan using plany_pkey on plany pl
(cost=0.00..4.49 rows=1 width=17) (actual time=0.09..0.11 rows=1 loops=1)
Index Cond: (id_planu = 508)
-> Seq Scan on linia_trasy lt (cost=0.00..1.14 rows=14
width=12) (actual time=0.02..0.12 rows=14 loops=1)
If I add "and k.id_trasy=lt.id_trasy" into where clause (duplicate), the
query works fine.
Regards,
Tomasz Myrta
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Subject: Re: explicit joins wrong planning
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