On Thu, Apr 21, 2011 at 9:30 AM, Claudio Freire <klaussfreire@xxxxxxxxx> wrote: > On Thu, Apr 21, 2011 at 4:05 AM, Brendan Jurd <direvus@xxxxxxxxx> wrote: >> >> "IMMUTABLE indicates that the function cannot modify the database and >> always returns the same result when given the same argument values" >> >> Emphasis on "always". If the result of the function, given the same >> argument values, can be different after a SET, then it doesn't qualify >> for immutability. At least, that's my understanding. > > That's a ridiculous use of the word "Immutable" > > In any CS class, the timezone would be an implicit input to the > function. So it would be immutable in *that* sense (it also takes > timezone into consideration). > > Perhaps the optimizer should take contextual information that cannot > change inside a query as input too. > In any case, the point is that the CE check (which is what CE cares about) is indeed immutable in the PG sense. If it is instantiated with a STABLE expression, it would still be equivalent to IMMUTABLE within the transaction - which is what CE cares about. Am I missing something? -- Sent via pgsql-performance mailing list (pgsql-performance@xxxxxxxxxxxxxx) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-performance
