Re: Created Index is not used - Mailing list pgsql-performance

From Ragnar
Subject Re: Created Index is not used
Date
Msg-id 1140699807.5728.42.camel@localhost.localdomain
Whole thread Raw
In response to Created Index is not used  (Kjeld Peters <kjeld.peters@profiling-company.de>)
List pgsql-performance
On fim, 2006-02-23 at 13:35 +0100, Kjeld Peters wrote:
> Select and update statements are quite slow on a large table with more
> than 600,000 rows. The table consists of 11 columns (nothing special).
> The column "id" (int8) is primary key and has a btree index on it.
>
> The following select statement takes nearly 500ms:
>
> SELECT * FROM table WHERE id = 600000;
>
> A prepending "EXPLAIN" to the statement reveals a seq scan:
>
> EXPLAIN SELECT * FROM table WHERE id = 600000;
>
> "Seq Scan on table  (cost=0.00..15946.48 rows=2 width=74)"
> "  Filter: (id = 600000)"

> I tried a full vacuum and a reindex, but had no effect. Why is
> PostgreSQL not using the created index?

try one of:

SELECT * FROM table WHERE id = '600000';
SELECT * FROM table WHERE id = 600000::int8;
PostgreSQL 8+

gnari




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