The actual table I noticed the problem has a million rows and it still
doesn't use indexing
Reid Thompson wrote:
> 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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>>
>> http://www.postgresql.org/docs/faq
>>
>
>
>
--
Christo Du Preez
Senior Software Engineer
Mecola IT
Mobile: +27 [0]83 326 8087
Skype: christodupreez
Website: http://www.locateandtrade.co.za