On Fri, Apr 27, 2018 at 11:35 AM, Andrew Gierth <and...@tao11.riddles.org.uk> wrote: >>>>>> "Robert" == Robert Haas <robertmh...@gmail.com> writes: > Robert> One idea that occurred to me is to somehow record -- I guess in > Robert> pg_class using non-transactional updates -- the last cutoff XID > Robert> used to vacuum any given table. Then we could just make a rule > Robert> that you can't vacuum the TOAST table with an XID that's newer > Robert> than the last one used for the main table. That would preserve > Robert> the property that you can vacuum the tables separately while > Robert> avoiding dangling pointers. But that's obviously not > Robert> back-patchable, > > The suggestion made previously (in a historical thread) was to use an > entry in the reloptions field for this, at least in back branches. It > would be necessary for vacuum to add the entry initially in a normal > transactional update, after which it could be updated inplace.
Yeah, I suppose. Sounds pretty rickety to me, though. Maybe I'm just a pessimist. -- Robert Haas EnterpriseDB: http://www.enterprisedb.com The Enterprise PostgreSQL Company
