On 2017-02-24 01:59:01 -0500, Tom Lane wrote: > Andres Freund <and...@anarazel.de> writes: > > On 2017-02-23 17:28:26 -0500, Tom Lane wrote: > >> Maybe it's time to convert that to a doubly-linked list. > > > Yes, I do think so. Given that we only have that for full blocks, not > > for small chunks, the cost seems neglegible. > > That would also, partially, address the performance issue > > http://archives.postgresql.org/message-id/d15dff83-0b37-28ed-0809-95a5cc7292ad%402ndquadrant.com > > addresses, in a more realistically backpatchable manner. > > Yeah, I was wondering if we could get away with back-patching such a > change. In principle, nothing outside aset.c should know what's in the > header of an AllocBlock, but ...
You'd need to go through a fair amount of intentional pain to be affected by a change AllocBlockData's structure. We could add the ->prev pointer to the end of AllocBlockData's definition to make it less likely that one would be affected in that unlikely case - but I'm a bit doubtful it's worth the trouble. - Andres -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
