On Fri, 2008-09-12 at 13:53 +0300, Hannu Krosing wrote: > 4. Slave keeps copies of removed pages or rows when WAL apply removes > old versions . > > Possible ways to do this > > * inside Slave - have some backup store tied to OldestXmin intervals > > * variant 1 - have one global store, accessed through shared mem > * variant 2 - present removed pages to interested backends and > let them (decide to) keep them > > * outside Slave - having file system keep old snapshots as long as > needed, still must tie to OldestXmin intervals, but most of work done by > storage layer (SAN or overlay file system).
Possible options for "outside Slave" filesystem snapshooting - ZFS ( http://en.wikipedia.org/wiki/ZFS ) is very likely usable Linux LVM + XFS may be usable - http://arstechnica.com/articles/columns/linux/linux-20041013.ars Possibly also http://en.wikipedia.org/wiki/Btrfs . ---------------- Hannu -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
