On Thu, Mar 31, 2011 at 2:59 PM, Bruce Momjian <br...@momjian.us> wrote: > Bruce Momjian wrote: >> > Yeah, I think this change would have the effect of moving the freeze >> > limit by one (or two?) counts. Given the moving nature of values >> > returned by ReadNewTransactionId this would probably have no practical >> > effect. Still, the code as is seems more natural to me (Tom wrote this >> > bit IIRC, not me). >> >> I am now thinking the code is correct --- it maps values from 0 to >> FirstNormalTransactionId into the top of the (unsigned) xid range. >> Unless someone objects, I will add a C comment about this behavior so >> future readers are not confused. > > OK, now I think it is wrong. :-) > > The effect is to map max xid + 1 to max xid - > FirstNormalTransactionId(3) + 1, which makes the xid look like it is > going backwards, less than max xid --- not good.
The XID space is *circular*. -- 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
