On Mon, Mar 6, 2017 at 12:44 PM, Andres Freund <and...@anarazel.de> wrote: > On 2017-03-06 12:40:18 -0500, Robert Haas wrote: >> 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. > > I agree, but to me it seems the only fix would be to just yank out the > whole optimization?
Dunno, haven't looked into it. -- 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
