Re: wrong query plan in 7.1beta3

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Kovacs Zoltan <kovacsz(at)pc10(dot)radnoti-szeged(dot)sulinet(dot)hu>
Cc: pgsql-hackers(at)postgresql(dot)org, pgsql-sql(at)postgresql(dot)org
Subject: Re: wrong query plan in 7.1beta3
Date: 2001-01-27 16:20:52
Message-ID: 21888.980612452@sss.pgh.pa.us
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Kovacs Zoltan <kovacsz(at)pc10(dot)radnoti-szeged(dot)sulinet(dot)hu> writes:
> There seems to be an optimizer problem in 7.1beta3. The query you can see
> below worked fast in 7.0.2 but in 7.1beta3 is rather slow. The problem is
> that an 'index scan' has been changed to a 'seq scan'. Details:

This is fixed in current sources: I get

Subquery Scan sd_user_grant (cost=5.16..5.22 rows=1 width=61)
-> Aggregate (cost=5.16..5.22 rows=1 width=61)
-> Group (cost=5.16..5.18 rows=3 width=61)
-> Sort (cost=5.16..5.16 rows=3 width=61)
-> Nested Loop (cost=0.00..5.14 rows=3 width=61)
-> Seq Scan on pg_shadow (cost=0.00..1.01 rows=1 width=32)
-> Index Scan using sd_grant_pkey on sd_grant (cost=0.00..4.07 rows=3 width=29)

regards, tom lane

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