On Wed, Nov 9, 2022 at 6:10 PM Andres Freund <and...@anarazel.de> wrote: > And thinking about it, it'd be quite bad if the horizon worked that way. You > can easily construct a workload where every single xid would "skewer" some > chain, never allowing the horizon to be raised.
Your whole scenario is one involving a insert of a tuple by XID 10, which is then updated by XID 5 -- a lower XID. Obviously that's possible, but it's relatively rare. I have to imagine that the vast majority of updates affect tuples inserted by an XID before the XID of the updater. My use of the term "skewer" was limited to updates that look like that. So I don't know what you mean about never allowing the horizon to be raised. -- Peter Geoghegan
