Alvaro Herrera wrote: > I think the previous patch to snapmgr.c was mistaken. Instead of fixing > a single trouble spot, we're better off fixing PushActiveSnapshot so > that any use of it that involves a snapshot that's subject to a future > command counter update should create a new copy.
For a while I was thinking this was useless, because surely CurrentSnapshot would always be pointing to static storage, no? However I realized that this is not the case in serializable transactions, because such transaction need to register the current snapshot and thus it creates a copy of it. So the problem is that in a serializable snapshot, ActiveSnapshot may be pointing to the exact same copy that a CommandCounterIncrement would modify. -- Alvaro Herrera http://www.CommandPrompt.com/ PostgreSQL Replication, Consulting, Custom Development, 24x7 support -- Sent via pgsql-general mailing list (pgsql-general@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-general
