Look into the immutable flag on function creation:
http://www.postgresql.org/docs/8.1/interactive/xfunc-volatility.html
On Wed, 19 Apr 2006, Clodoaldo Pinto wrote:
I'm building a function caller() in which a certain function called()
will be called many times in from clauses with the same arguments and
I'm wondering if is there a performance penalty for that or if the sql
engine is smart enough to call called() only once.
I tried to substitute called() in the from clauses for a temporary
table created first in caller() but it refuses to build caller() with
the message "ERROR: relation "temp_table_name" does not exist". It
does not exist in build time but it will exist in run time.
Regards, Clodoaldo Pinto
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