Is there a particular reason why CLUSTER isn't MVCC-safe? It seems to me
that it would be trivial to fix, by using SnapshotAny instead of
SnapshotNow, and not overwriting the xmin/xmax with the xid of the
cluster command.
I feel that I must missing something, or someone would've already fixed
it a long time ago...
Csaba, you mentioned recently
(http://archives.postgresql.org/pgsql-hackers/2007-03/msg00027.php) that
you're actually using the MVCC-violation to clean up tables during a
backup. Can you tell us a bit more about that? Would you be upset if we
shut that backdoor?
In any case, the MVCC-violation needs to be documented. I'll send a doc
patch to pgsql-patches shortly.
-- Heikki Linnakangas EnterpriseDB http://www.enterprisedb.com