Re: Toast issues with OldestXmin going backwards

>>>>> "Robert" == Robert Haas <robertmhaas(at)gmail(dot)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.

--
Andrew (irc:RhodiumToad)