On Fri, Oct 11, 2013 at 4:05 PM, Andres Freund <and...@2ndquadrant.com> wrote: >> Maybe. The original reason we added compact commits was because we >> thought that making unlogged tables logged and visca/versa was going >> to require adding still more stuff to the commit record. I'm no >> longer sure that's the case and, in any case, nobody's worked out the >> design details. But I can't help thinking more stuff's likely to come >> up in the future. I'm certainly willing to entertain proposals for >> restructuring that, but I don't really want to just throw it out. > > Well, what I am thinking of - including & reading data depending on a > flag in ->xinfo - would give you extensibility without requiring > different types of commits. And it would only blow up the size by > whatever needs to be included.
Hard to comment without seeing the patch. Sounds like it could be reasonable, if it's not too ugly. >> >> Maybe you should just skip replay of transactions with no useful >> >> content. >> > >> > Yes, I have thought about that as well. But I dislike it - how do we >> > define "no useful content"? >> >> The only action we detected for that XID was the commit itself. > > What if the transaction was intentionally done to get an xid + timestamp > in a multimaster system? What if it includes DDL but no logged data? Do > we replay a transaction because of the pg_shdepend entry when creating a > table in another database? None of these things seem particularly alarming to me. I don't know whether that represents a failure of imagination on my part or undue alarm on your part. :-) -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers