Andrew Gierth wrote: > >>>>> "Alvaro" == Alvaro Herrera <alvhe...@2ndquadrant.com> writes: > > >> (It can, AFAICT, be inside the currently valid range due to > >> wraparound, i.e. without there being a valid pg_multixact entry for > >> it, because AFAICT in 9.2, once the mxid is hinted dead it is never > >> again either looked up or cleared, so it can sit in the tuple xmax > >> forever, even through multiple wraparounds.) > > Alvaro> HeapTupleSatisfiesVacuum removes very old multixacts > > It does nothing of the kind; it only marks them HEAP_XMAX_INVALID. The > actual mxid remains in the tuple xmax field. > > The failing mxids in the case I analyzed on -bugs are failing _in spite > of_ being already hinted HEAP_XMAX_INVALID, because the code path in > question doesn't check that.
Ah, right. I had some code to reset HEAP_XMAX_IS_MULTI early on but somebody didn't like it and we removed it; and we also removed some of the checks for HEAP_XMAX_INVALID we had, or perhaps didn't extend them to every place that needed them. It's not critical now anyway; the patch I posted (or some variation thereof) should suffice as a fix. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
