Re: Mechanics of Select - Mailing list pgsql-general

From Tom Lane
Subject Re: Mechanics of Select
Date
Msg-id 11648.1202687109@sss.pgh.pa.us
Whole thread Raw
In response to Mechanics of Select  (Willem Buitendyk <willem@pcfish.ca>)
List pgsql-general
Willem Buitendyk <willem@pcfish.ca> writes:
> I have the following function that returns the first day of the next
> month from whatever date is inserted.  If I use this as part of a select
> statement then it takes almost twice as long to perform.  Is this
> because for each scanned record this function is being called?  If so
> any ideas how I could make this only occur once?

Don't declare it VOLATILE, when (AFAICS) you have no reason to.
It would be evaluated only once if it were marked IMMUTABLE.

BTW, I think you're doing it the hard way --- this could almost
certainly be a one-liner if you were using the available date
arithmetic facilities.

            regards, tom lane

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