From: Marc G. Fournier <scrappy@postgresql.org>
To: pgsql-performance@postgresql.org
Subject: getting an index to work with partial indices ...
Date: Mon, 29 Aug 2005 16:56:15 -0300 (ADT)
Message-ID: <20050829165335.X1044@ganymede.hub.org> (raw)
Try as I might, I can't seem to get it to work ... table has >9million
rows in it, I've created an index "using btree ( priority ) where priority
< 0;", where the table distribution looks like:
priority | count
----------+---------
-2 | 138435
-1 | 943250
1 | 3416
9 | 1134171
| 7276960
(5 rows)
And it still won't use the index:
# explain update table set priority = -3 where priority = -1;
QUERY PLAN
------------------------------------------------------------------
Seq Scan on table (cost=0.00..400735.90 rows=993939 width=278)
Filter: (priority = -1)
(2 rows)
But, ti will if I try 'priority = -2' ... what is teh threshhold for using
the index? obviously 10% of the records is too high ...
thanks ...
----
Marc G. Fournier Hub.Org Networking Services (http://www.hub.org)
Email: scrappy@hub.org Yahoo!: yscrappy ICQ: 7615664
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To: pgsql-performance@postgresql.org
Cc: scrappy@postgresql.org
Subject: Re: getting an index to work with partial indices ...
In-Reply-To: <20050829165335.X1044@ganymede.hub.org>
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