Re: Static functions

["Gurjeet Singh" <singh.gurjeet@xxxxxxxxx>]

On Sat, Oct 4, 2008 at 6:06 PM, Gregory Stark <stark@xxxxxxxxxxxxxxxx> wrote:

"Gurjeet Singh" <singh.gurjeet@xxxxxxxxx> writes:

> On Sat, Oct 4, 2008 at 8:49 AM, Tom Lane <tgl@xxxxxxxxxxxxx> wrote:
>
>> "Gurjeet Singh" <singh.gurjeet@xxxxxxxxx> writes:
>> > Shouldn't PG make all efforts to not execute something when the result is
>> > already known?
>>
>> Not if said effort would cost more than is saved, which would be by far
>> the most likely result if we tried to cache all function results.
>>
>
> Sorry Tom, I confused STABLE  with IMMUTABLE; my bad.

No, this is equally untrue for immutable.

Yup... I realized that after a bit of more testing after the mail... Immutable functions are single-call-per-command only of you are passing constants-only as parameters; if we have an _expression_ involving columns, then they will be called for every row.

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