Thanks Tom, Yes, we've discussed adding some kind of optional identity information to the object, it remains a potential course of action.
Paul On Tue, Apr 1, 2008 at 2:37 PM, Tom Lane <[EMAIL PROTECTED]> wrote: > "Paul Ramsey" <[EMAIL PROTECTED]> writes: > > The "optimized" form gets cached and retrieved from a memory context. > > Each time the function is run within a statement it checks the cache, > > and sees if one of its arguments are the same as the last time around. > > If so, it uses the prepared version of that argument. If not, it > > builds a new prepared version and caches that. > > > The key here is being able to check the identify of the arguments... > > is this argument A the same as the one we processed last time? One way > > is to do a memcmp. But it seems likely that PgSQL knows exactly > > whether it is running a nested loop, or a literal, and could tell > > somehow that argument A is the same with each call. > > Not really. Certainly there's no way that that information would > propagate into function calls. > > In the special case where your argument is a literal constant, I think > there is enough information available to detect that that's the case > (look at get_fn_expr_argtype). But if it's not, there's no very good > way to know whether it's the same as last time. > > Perhaps it would be worth changing your on-disk storage format to allow > cheaper checking? For instance include a hash value. > > regards, tom lane > -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
