Re: Freeing transient memory in aggregate functions

Matt Magoffin <postgresql.org@msqr.us> writes:
> I’m essentially doing a datumCopy() on every non-null input value.

If you're doing that in the aggContext, you definitely need to free
the prior one(s).

> I was wondering if there is a way to free the previously copied datum, since I don’t really need it anymore?
Somethinglike 

>   if (state->last != NULL) {
>     pfree(state->last);
>   }

Not quite like that.  Look into nodeAgg.c, which solves a similar problem
for the transvalues themselves with code like

            /* forget the old value, if any */
            if (!oldIsNull && !pertrans->inputtypeByVal)
                pfree(DatumGetPointer(oldVal));

            regards, tom lane