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
>
>
> ---------------------------(end of broadcast)---------------------------
> TIP 3: Have you checked our extensive FAQ?
>
> http://www.postgresql.org/docs/faq