Re: BUG #5530: Default cost of crypt causes poor decisions - Mailing list pgsql-bugs

From Tom Lane
Subject Re: BUG #5530: Default cost of crypt causes poor decisions
Date
Msg-id 25610.1277850091@sss.pgh.pa.us
Whole thread Raw
In response to BUG #5530: Default cost of crypt causes poor decisions  ("Baegle" <al@wifiny.org>)
List pgsql-bugs
"Baegle" <al@wifiny.org> writes:
> The default cost of crypt() is 1, but crypt is intentionally a high cost
> function. This mis-match between assigned cost and actual cost causes the
> query planner to use crypt too soon and slows down execution of queries
> significantly. The cost of the function should be more congruent with it's
> intended cost.

Perhaps, but the same could be said of most of the contrib/pgcrypto
functions, no?  Which ones do you think should have a nondefault cost,
and what should we set it to?

Also, it'd be easier to persuade people this is worth worrying about if
you showed a real-world case where it's a problem.  crypt() doesn't seem
like a function that would be very likely to be used in contexts where
this'd matter.

            regards, tom lane

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