From: Tom Lane <tgl@sss.pgh.pa.us>
To: Mario Splivalo <mario.splivalo@megafon.hr>
Cc: pgsql-performance@postgresql.org
Subject: Re: Forcing seq_scan off for large table joined with tiny table yeilds improved performance
Date: Mon, 30 Mar 2009 10:16:11 -0400
Message-ID: <3028.1238422571@sss.pgh.pa.us> (raw)
In-Reply-To: <49D0D237.7020308@megafon.hr>
References: <49D0D237.7020308@megafon.hr>
Mario Splivalo <mario.splivalo@megafon.hr> writes:
> -> Bitmap Heap Scan on photo_info_data u (cost=39134.84..63740.08
> rows=109024 width=50) (actual time=270.464..270.469 rows=3 loops=2)
> Recheck Cond: ((u.field_name)::text = (t.key)::text)
> -> Bitmap Index Scan on photo_info_data_pk
> (cost=0.00..39107.59 rows=109024 width=0) (actual time=270.435..270.435
> rows=3 loops=2)
> Index Cond: ((u.field_name)::text = (t.key)::text)
You need to figure out why that rowcount estimate is off by more than
four orders of magnitude :-(
regards, tom lane
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To: pgsql-performance@postgresql.org
Cc: tgl@sss.pgh.pa.us, mario.splivalo@megafon.hr
Subject: Re: Forcing seq_scan off for large table joined with tiny table yeilds improved performance
In-Reply-To: <3028.1238422571@sss.pgh.pa.us>
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