On Wed, Mar 1, 2017 at 5:55 PM, Andres Freund <and...@anarazel.de> wrote: > The issue was that on 32bit platforms the Datum returned by some > functions (int2int4_sum in this case) isn't actually a separately > allocated Datum, but rather just something embedded in a larger > struct. That, combined with the following code: > if (!peraggstate->resulttypeByVal && !*isnull && > !MemoryContextContains(CurrentMemoryContext, > > DatumGetPointer(*result))) > seems somewhat problematic to me. MemoryContextContains() can give > false positives when used on memory that's not a distinctly allocated > chunk, and if so, we violate memory lifetime rules. It's quite > unlikely, given the required bit patterns, but nonetheless it's making > me somewhat uncomfortable. > > Do others think this isn't an issue and we can just live with it?
I think it's 100% broken to call MemoryContextContains() on something that's not guaranteed to be a palloc'd chunk. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
