Re: getting an index to work with partial indices ... - Mailing list pgsql-performance

From Tom Lane
Subject Re: getting an index to work with partial indices ...
Date
Msg-id 12790.1125346745@sss.pgh.pa.us
Whole thread Raw
In response to getting an index to work with partial indices ...  ("Marc G. Fournier" <scrappy@postgresql.org>)
List pgsql-performance
"Marc G. Fournier" <scrappy@postgresql.org> writes:
> But, ti will if I try 'priority = -2' ... what is teh threshhold for using
> the index?  obviously 10% of the records is too high ...

Depends on a lot of factors, but usually somewhere between 1% and 10%.
(The new bitmap index scan code in 8.1 should be workable for higher
percentages.)  If this doesn't seem to square with reality for you,
you might try reducing random_page_cost.

            regards, tom lane

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