On Sat, Dec 22, 2012 at 2:25 AM, David Johnston <pol...@yahoo.com> wrote:
> You have defined the function as "IMMUTABLE". The system is allowed to cache
> the results of a given call (i.e. "ps3(2)") and return the value without
> actually executing the function ("never executed"). Your second example
> returns "1" without a warning regarding the "2" invocation due to this. The
> Query Plan you show also matches this behavior.
Further reading on this subject:
http://www.postgresql.org/docs/9.1/static/xfunc-volatility.html
See particularly the second paragraph after the bullet list.
ChrisA
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