Stephen Frost wrote: > * Stephen Frost (sfr...@snowman.net) wrote: > > I have the pre-upgrade database and can upgrade/rollback/etc that pretty > > easily. Note that the table contents weren't changed during the > > upgrade, of course, and so the 9.2.6 instance has HEAP_XMAX_IS_MULTI set > > while t_xmax is 6849409 for the tuple in question- even though > > pg_controldata reports NextMultiXactId as 1601462 (and it seems very > > unlikely that there's been a wraparound on that in this database..). > > Further review leads me to notice that both HEAP_XMAX_IS_MULTI and > HEAP_XMAX_INVALID are set: > > t_infomask | 6528 > > 6528 decimal -> 0x1980 > > 0001 1001 1000 0000 > > Which gives us: > > 0000 0000 1000 0000 - HEAP_XMAX_LOCK_ONLY > 0000 0001 0000 0000 - HEAP_XMIN_COMMITTED > 0000 1000 0000 0000 - HEAP_XMAX_INVALID > 0001 0000 0000 0000 - HEAP_XMAX_IS_MULTI > > Which shows that both HEAP_XMAX_INVALID and HEAP_XMAX_IS_MULTI are set.
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. -- Álvaro Herrera http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, 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