On Wed, Apr 21, 2010 at 9:37 AM, Simon Riggs <si...@2ndquadrant.com> wrote: > On Wed, 2010-04-21 at 15:27 +0300, Heikki Linnakangas wrote: > >> Given the discussion about the cyclic nature of XIDs, it would be good >> to add an assertion that when a new XID is added to the array, it is >> >> a) larger than the biggest value already in the array >> (TransactionIdFollows(new, head)), and >> b) not too far from the smallest value in the array to confuse binary >> search (TransactionIdFollows(new, tail)). > > We discussed this in November. You convinced me it isn't possible for > older xids to stay in the standby because anti-wraparound vacuums would > conflict and kick them out. The primary can't run with wrapped xids and > neither can the standby. I think that is correct. > > Adding an assertion isn't going to do much because it's unlikely anybody > is going to be running for 2^31 transactions with asserts enabled. > > Worrying about things like this seems strange when real and negative > behaviours are right in our faces elsewhere. Performance and scalability > are real world concerns.
I think the assert is a good idea. If there's no real problem here, the assert won't trip. It's just a safety precaution. ...Robert -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
