Thread: cost variable into function

cost variable into function

From

"Alain Roger"

Date:

19 October 2008, 14:03:52

Hi,

i created a stored procedure (function) under postgreSQL and when i checked deeper into my DB, this is what i get:
....
END;
$BODY$
LANGUAGE 'plpgsql' VOLATILE
COST 100;
ALTER FUNCTION myschema.get_count_languages(character varying) OWNER TO myuser;

to what corresponds the parameter COST 100 ?
it is the first time i see that :-(
thx.
--
Alain
------------------------------------
Windows XP SP3
PostgreSQL 8.2.4 / MS SQL server 2005
Apache 2.2.4
PHP 5.2.4
C# 2005-2008

Re: cost variable into function

From

"Grzegorz Jaśkiewicz"

Date:

19 October 2008, 14:18:41

that's for planner to know. You can estimate cost in there, of that procedure. I usually use select * from something limit 1 times number of rows that procedure returns on average. But I am sure, some more smart people here would have different ways to set it.

Re: cost variable into function

From

hubert depesz lubaczewski

Date:

19 October 2008, 14:19:50

On Sun, Oct 19, 2008 at 04:03:47PM +0200, Alain Roger wrote:
> i created a stored procedure (function) under postgreSQL and when i checked
> deeper into my DB, this is what i get:
> ....
>     END;
> $BODY$
>   LANGUAGE 'plpgsql' VOLATILE
>   COST 100;
> ALTER FUNCTION myschema.get_count_languages(character varying) OWNER TO
> myuser;
> to what corresponds the parameter COST 100 ?

check the explanation here:
http://www.postgresql.org/docs/current/interactive/sql-createfunction.html

Best regards,

depesz

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