On Sat, Oct 27, 2012 at 8:41 PM, Heikki Linnakangas <hlinnakan...@vmware.com> wrote: > If the pointers are stored as simple 4-byte integers, you probably could > assume that they're atomic, and won't be torn.
Actually I think any fixed-size data structure would be fine. We're worried about storage on disk here, not in memory. As long as the pointers don't move around on the page then if part of a page is written and part not then the only pointer possibly corrupted would be the one spanning the old and new partial pages. That could be avoided or detected easily. The problem with torn pages on heap pages comes about only because tuples are variable sized. As a result the page has line pointers that need to be in sync with other parts of the page and vacuum needs to be able to move tuples around on the page. (Hm. I wonder if we could actually get away with only doing full page writes on vacuum if we could detect torn pages from vacuum reliably and avoid trying to read any data from them until they get restored by the full page write.) -- greg -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
