Re: seq scan over 3.3 million rows instead of single key index access - Mailing list pgsql-performance

Andrus <kobruleht2@hot.ee> schrieb:

> There are  indexes on   rid(dokumnr) and dok(dokumnr) and dokumnr is int.
> Instead of using single key index, 8.1.4 scans over whole rid table.
> Sometimes idtelluued can contain more than single row so replacing join
> with equality is not possible.
>
> How to fix ?
>
> Andrus.
>
> CREATE TEMP TABLE idtellUued(dokumnr INT) ON COMMIT DROP;
> INSERT INTO idtellUued VALUES(1249228);
> explain analyze  select 1
>   from dok JOIN rid USING(dokumnr)
> JOIN idtellUued USING(dokumnr)

Try to analyse the idtellUued-table after the insert. The planner has no
knowledge that this table contains only one or e few rows, the planner
assume 1000 (iirc) in this table.


Andreas
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