Heikki Linnakangas <[EMAIL PROTECTED]> writes: > 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.
The reason it's not trivial is that you also have to preserve the t_ctid links of update chains. If you look into VACUUM FULL, a very large part of its complexity is that it moves update chains as a unit to make that possible. (BTW, I believe the problem Pavan Deolasee reported yesterday is a bug somewhere in there --- it looks to me like sometimes the same update chain is getting copied multiple times.) regards, tom lane ---------------------------(end of broadcast)--------------------------- TIP 9: In versions below 8.0, the planner will ignore your desire to choose an index scan if your joining column's datatypes do not match