On Mon, Feb 9, 2015 at 1:58 PM, bkrug <bk...@usatech.com> wrote: > Couldn't postgres reserve a special XID that is never available for normal > transactions but that indicates that any transaction can see it because it > is so old? Then instead of constantly having to freeze old XIDs each time > the XID is going to wrap, vacuum can just set it to the special XID and > never touch it again unless something really changes. >
It changed in recent versions (9.3 or 9.4, I don't recall exactly which) and moved to tuple header, but what you described is exactly what was done, the xid was 2. Anyway, an already frozen tuple won't be "re-frozen" again. Regards, -- Matheus de Oliveira Analista de Banco de Dados Dextra Sistemas - MPS.Br nível F! www.dextra.com.br/postgres
