Rob Sargent wrote:
Richard Huxton wrote:
Rob Sargent wrote:
pg-admin is showing 'COST 100' and 'ROWS 1000' for my explicitly
VOLATILE functions.
Thanks for the pointer back to CREATE FUNCTION docs. That would have
told me that those value are indeed the defaults. I guess I'm somewhat
surprised that they are in fact defautled. "COST" is too arbitrary for
me to comment on, but my functions' results sets fall on both sides of
1000 rows, so I'm not sure giving this value to the planner does a lot
of good. Luckily, my functions are typically pretty much stand-alone
calls, and not part of some larger query.
If your functions are all called at the top-level then indeed it doesn't
matter. At a low level though, telling the planner function F1 costs
1000 times more than F2 is useful.
--
Richard Huxton
Archonet Ltd
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