From: SZŰCS Gábor <surrano@mailbox.hu>
To: pgsql-performance@postgresql.org
Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1
Date: Wed, 30 Apr 2003 13:00:40 +0200
Message-ID: <004401c30f07$c07f45e0$0a03a8c0@fejleszt2> (raw)
References: <00db01c30e54$1ab272d0$0a03a8c0@fejleszt2>
<26550.1051627993@sss.pgh.pa.us>
<011101c30e68$f056bdb0$0a03a8c0@fejleszt2>
<18324.1051657553@sss.pgh.pa.us>
----- Original Message -----
From: "Tom Lane" <tgl@sss.pgh.pa.us>
Sent: Wednesday, April 30, 2003 1:05 AM
> "=?iso-8859-2?B?U1rbQ1MgR+Fib3I=?=" <surrano@mailbox.hu> writes:
> > ---------------------------- 7.2.1
PLAN ---------------------------------
> > -> Seq Scan on valuta (cost=0.00..1.06 rows=6 width=4) (actual
time=0.02..0.11 rows=6 loops=2)
> >
> > ---------------------------- 7.3.2
PLAN ---------------------------------
> > -> Seq Scan on valuta
(cost=0.00..20.00 rows=1000 width=4) (actual time=0.02..0.06 rows=6 loops=2)
>
> Ah, there's the problem. You never vacuumed or analyzed "valuta", so
> the 7.3 planner didn't know it had only six rows, and chose a plan that
> was more appropriate for a larger table. The thousand-row estimate is
> the tipoff, because that's the default assumption when there are no
> stats.
>
> regards, tom lane
Thanks!
VACUUM ANALYZE really worked and I learned something new.
The strange part is, that I think I issued a "VACUUM ANALYZE;" (that should
do all the tables, right?) a couple of weeks before because of another
problem (it didn't help that time, tho)
G.
--
while (!asleep()) sheep++;
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To: pgsql-sql@postgresql.org
Cc: surrano@mailbox.hu, pgsql-performance@postgresql.org
Subject: Re: Query Plan far worse in 7.3.2 than 7.2.1
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