Re: Raising stop and warn limits

On Sun, Jun 21, 2020 at 01:35:13AM -0700, Noah Misch wrote:
> In brief, I'm proposing to raise xidWrapLimit-xidStopLimit to 3M and
> xidWrapLimit-xidWarnLimit to 40M.  Likewise for mxact counterparts.

Here's the patch for it.

> 1. VACUUM, to advance a limit, may assign IDs subject to one of the limits.
>    VACUUM formerly consumed XIDs, not mxacts.  It now consumes mxacts, not
>    XIDs.

Correction: a lazy_truncate_heap() at wal_level!=minimal does assign an XID,
so XID consumption is impossible with "VACUUM (TRUNCATE false)" but possible
otherwise.  "VACUUM (ANALYZE)", which a DBA might do by reflex, also assigns
XIDs.  (These corrections do not affect $SUBJECT.)