Re: Toast issues with OldestXmin going backwards

>>>>> "Robert" == Robert Haas <robertmhaas@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.

-- 
Andrew (irc:RhodiumToad)