| From: | Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> |
|---|---|
| To: | Heikki Linnakangas <heikki(at)enterprisedb(dot)com> |
| Cc: | pgsql-hackers(at)postgreSQL(dot)org |
| Subject: | Re: Function execution costs 'n all that |
| Date: | 2007-01-15 17:19:03 |
| Message-ID: | 17077.1168881543@sss.pgh.pa.us |
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| Lists: | pgsql-hackers |
Heikki Linnakangas <heikki(at)enterprisedb(dot)com> writes:
> Tom Lane wrote:
>> If we go this route it seems like we'll need four more columns in
>> pg_proc (cost estimation function OID, rowcount estimation function OID,
>> fallback cost constant, fallback rowcount constant).
> What would the fallbacks be for?
By "fallback" I meant "this is what to use if no estimation function is
provided".
I'm envisioning that the CREATE FUNCTION syntax would add optional
clauses
COST function-name-or-numeric-constant
ROWS function-name-or-numeric-constant
that would be used to fill these columns.
regards, tom lane
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