Thread: index selection by query planner

index selection by query planner

From
Rohit Gaddi
Date:
Hi,
 
I have a table with two indices on the same column, one of which is a partial index. I would like the query planner to use the partial index whenever the query condition lies in the range of the partial index as it would yield better performance. Is there any way to enforce the ordering for the indices? How does the query planner decide which index to use when a particular query is fired?  'Explain Analyze' showed the total index being used in a situation that could be fulfiled by the partial index.
 
Thanks,
Rohit


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Re: index selection by query planner

From
Josh Berkus
Date:
Rohit,

> I have a table with two indices on the same column, one of which is a
> partial index. I would like the query planner to use the partial index
> whenever the query condition lies in the range of the partial index as it
> would yield better performance. Is there any way to enforce the ordering
> for the indices? How does the query planner decide which index to use when
> a particular query is fired?  'Explain Analyze' showed the total index
> being used in a situation that could be fulfiled by the partial index.

Please post the query, the table and index definitions, and the EXPLAIN
ANALYZE to the PGSQL-PERFORMANCE mailing list.  Thanks!

--
Josh Berkus
Aglio Database Solutions
San Francisco