Avoid consuming an XID during vac_truncate_clog(). vac_truncate_clog() uses its own transaction ID as the comparison point in a sanity check that no database's datfrozenxid has already wrapped around "into the future". That was probably fine when written, but in a lazy vacuum we won't have assigned an XID, so calling GetCurrentTransactionId() causes an XID to be assigned when otherwise one would not be. Most of the time that's not a big problem ... but if we are hard up against the wraparound limit, consuming XIDs during antiwraparound vacuums is a very bad thing.
Instead, use ReadNewTransactionId(), which not only avoids this problem but is in itself a better comparison point to test whether wraparound has already occurred. Report and patch by Alexander Korotkov. Back-patch to all versions. Report: <CAPpHfdspOkmiQsxh-UZw2chM6dRMwXAJGEmmbmqYR=yvm7-...@mail.gmail.com> Branch ------ REL9_2_STABLE Details ------- http://git.postgresql.org/pg/commitdiff/2e7f0c34aa6dd2f4c02f57d9dd5c37eeeb661198 Modified Files -------------- src/backend/commands/vacuum.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) -- Sent via pgsql-committers mailing list (pgsql-committers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-committers
