Simon Riggs wrote:
On Fri, 2009-01-16 at 16:33 +0200, Heikki Linnakangas wrote:
I don't think RecentGlobalXmin is good enough here:
! /*
! * We would like to set an accurate latestRemovedXid,
but there
! * is no easy way of obtaining a useful value. So we
use the
! * probably far too conservative value of
RecentGlobalXmin instead.
! */
! xlrec_delete.latestRemovedXid = RecentGlobalXmin;
! rdata[0].data = (char *) &xlrec_delete;
! rdata[0].len = SizeOfBtreeDelete;
RecentGlobalXmin is just a hint, it lags behind the real oldest xmin
that GetOldestXmin() would return. If another backend has a more recent
RecentGlobalXmin value, and has killed more recent tuples on the page,
the latestRemovedXid written here is too old.
What do you think we should do instead?
Dunno. Maybe call GetOldestXmin().
--
Heikki Linnakangas
EnterpriseDB http://www.enterprisedb.com
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