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Re: Question about a CIDR based query

From: siganos(at)gmail(dot)com (George Siganos)
To: pgsql-sql(at)postgresql(dot)org
Subject: Re: Question about a CIDR based query
Date: 2004-06-26 23:06:15
Message-ID: ebba5a93.0406261506.7a0f7558@posting.google.com (view raw or flat)
Thread:
Lists: pgsql-sql
I did a vacuum analyze before I run the following explain 

June_03=# explain select * from tmp where route >>='62.1.1.0/24';
                           QUERY PLAN                           
----------------------------------------------------------------
 Seq Scan on tmp  (cost=0.00..606.60 rows=14544 width=33)
   Filter: (route >>= '62.1.1.0/24'::cidr)
(2 rows)

The select returns just one route,
Thanks

josh(at)agliodbs(dot)com (Josh Berkus) wrote in message news:<200406250900(dot)08312(dot)josh(at)agliodbs(dot)com>...
> Georgos,
> 
> > select * from tmp where route >>= some_cidr
> 
> Can you post an EXPLAIN ANALYZE for this?   And when's the last time you ran 
> ANALYZE on the table?
> 
> > The index on route is not used and I get a sequential scan. The index is
> > used only for the <<= operator.
> 
> Most likely Postgres thinks that the >>= query is returning 60% of your table, 
> which makes indexes useless.
> 
> -- 
> Josh Berkus
> Aglio Database Solutions
> San Francisco
> 
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