Hi, On 2020-10-27 20:51:10 -0700, Andres Freund wrote: > On 2020-10-15 01:37:35 -0700, Andres Freund wrote: > > Attached is a *prototype* implemention of this concept, which clearly is > > lacking some comment work (and is intentionally lacking some > > re-indentation). > > > > I described my thoughts about how to limit the horizons for temp tables in > > https://www.postgresql.org/message-id/20201014203103.72oke6hqywcyhx7s%40alap3.anarazel.de > > Attached is an updated version of this patch. Quite a bit of polish, > added removal of the isTopLevel arguments added a7212be8b9e that are now > unnecessary, and changed the initialization of the temp table horizons > to be latestCompletedXid + 1 instead of just latestCompletedXid when no > xid is assigned. > > > > Besides comments this probably mainly needs a bit more tests around temp > > table vacuuming. Should have at least an isolation test that verifies > > that temp table rows can be a) vacuumed b) pruned away in the presence > > of other sessions with xids. > > I added an isolationtester test for this. It verifies that dead rows in > temp tables get vacuumed and pruned despite concurrent sessions having > older snapshots. It does so by forcing an IOS and checking the number of > heap fetches reported by EXPLAIN. I also added a companion test for > permanent relations, ensuring that such rows do not get removed. > > > Any comments? Otherwise I'll push that patch tomorrow.
Just pushed this. Let's see what the BF says... It's kinda cool how much more aggressive hot pruning / killtuples now is for temp tables. Greetings, Andres Freund
