On Wed, Apr 23, 2014 at 03:01:02PM -0300, Alvaro Herrera wrote: > Andres Freund wrote: > > On 2014-03-31 08:54:53 -0300, Alvaro Herrera wrote: > > > My conclusion here is that some part of the code is failing to examine > > > XMAX_INVALID before looking at the value stored in xmax itself. There > > > ought to be a short-circuit. Fortunately, this bug should be pretty > > > harmless. > > > > > > .. and after looking, I'm fairly sure the bug is in > > > heap_tuple_needs_freeze. > > > > heap_tuple_needs_freeze() isn't *allowed* to look at > > XMAX_INVALID. Otherwise it could miss freezing something still visible > > on a standby or after an eventual crash. > > I think what we should do here is that if we see that XMAX_INVALID is > set, we just reset everything to zero without checking the multixact > contents. Something like the attached (warning: hand-edited, line > numbers might be bogus) > > I still don't know under what circumstances this situation could arise. > This seems most strange to me. I would wonder about this to be just > papering over a different bug elsewhere, except that we know this tuple > comes from a pg_upgraded table and so I think the only real solution is > to cope.
Shouldn't we log something at least if we are unsure of the cause? -- Bruce Momjian <br...@momjian.us> http://momjian.us EnterpriseDB http://enterprisedb.com + Everyone has their own god. + -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
