Re: index on custom function; explain

On Tue, 2005-10-04 at 03:10 -0700, Jan Aerts wrote:
> Some additional thoughts: what appears to take the most time (i.e.
> account for the highest cost in the explain), is _not_ running the
> function itself (cost=0.00..0.01), but comparing the result from that
> function with the name1 column in the mappings table
> (cost=0.00..35935.05). Am I right? (See EXPLAIN in previous post.) If
> so: that's pretty strange, because the name1-column in the mappings
> table is indexed...

35935.05 is for the loop, 0.01 is for the operation within the loop.

What version of PostgreSQL is this? Some old versions were not good at
handling the IN ( ... ) clause.

Also, PostgreSQL doesn't always do a wonderful job of considering the
activities of a function into the design of the query plans. Sometimes
this can be a blessing, but not in this case.

Cheers,
Andrew.

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