Subject: Re: test / live environment, major performance difference
From: Reid Thompson <Reid.Thompson@ateb.com>
Reply-To: Reid.Thompson@ateb.com
To: Christo Du Preez <christo@mecola.com>
Cc: pgsql-performance@postgresql.org
In-Reply-To: <466EA078.20601@mecola.com>
References: <466EA078.20601@mecola.com>
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Date: Tue, 12 Jun 2007 09:45:20 -0400
Message-Id: <1181655920.19256.3.camel@jhereg>
Mime-Version: 1.0

try it with a table with 650K rows...

On Tue, 2007-06-12 at 15:32 +0200, Christo Du Preez wrote:
> Good day,
> 
> I have noticed that my server never uses indexing. No matter what I do.
> 
> As an example I took a table with about 650 rows, having a parentid
> field with an index on parentid.
> 
> EXPLAIN ANALYZE
> SELECT *
>   FROM layertype
> where parentid = 300;
> 
> On my laptop the explain analyze looks like this:
> 
> "Index Scan using fki_layertype_parentid on layertype  (cost=0.00..8.27
> rows=1 width=109)"
> "  Index Cond: (parentid = 300)"
> 
> and on the problem server:
> 
> "Seq Scan on layertype  (cost=0.00..20.39 rows=655 width=110)"
> "  Filter: (parentid = 300)"
> 
> .........
> 
> I have dropped the index, recreated it, vacuumed the table, just about
> everything I could think of, And there is just no way I can get the
> query planner to use the index.
> 
> PostgreSQL 8.2.3 on i686-pc-linux-gnu, compiled by GCC gcc (GCC) 4.1.2
> 20061115 (prerelease) (SUSE Linux)
> POSTGIS="1.2.1" GEOS="3.0.0rc4-CAPI-1.3.3" PROJ="Rel. 4.5.0, 22 Oct
> 2006" USE_STATS
> 
> 
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