On Thu, 2012-12-06 at 20:12 -0500, Stephen Frost wrote: > The command is 'FREEZE', which sounded to me like the transaction ID > would be set to FrozenXID, meaning that we wouldn't be able to tell if > the inserting transaction was before or after ours...
Freezing does lose information, but I thought that this sub-thread was about the HEAP_XMIN_COMMITTED optimization that was in the first version of the commit but removed in a later commit. Setting HEAP_XMIN_COMMITTED does not lose information. > Your analysis of the hint bits themselves sounds reasonable but it seems > independent of the issue regarding setting the actual transaction ID. Upon re-reading, my last paragraph was worded a little too loosely. "The interesting thing about HEAP_XMIN_COMMITTED is that it can be set preemptively if we know that the transaction will actually commit (aside from the visibility issues within the transaction)." That should really be: "aside from the visibility issues before it does commit". Anyway, the HEAP_XMIN_COMMITTED loading optimizations require more discussion, but I think they are worth pursuing. The simpler form is when the table is created and loaded in the same transaction, but there may be some more sophisticated approaches, as well. Regards, Jeff Davis -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers