On Tue, Apr 27, 2021 at 03:43:07PM +0200, Tomas Vondra wrote: > On 4/27/21 7:34 AM, Masahiko Sawada wrote: > > On Tue, Apr 27, 2021 at 8:07 AM Andres Freund <and...@anarazel.de> wrote: > > > On 2021-04-26 23:59:17 +0200, Tomas Vondra wrote: > > > > On 4/26/21 9:27 PM, Andres Freund wrote: > > > > > On 2021-04-26 15:31:02 +0200, Tomas Vondra wrote: > > > > > > I'm not sure what to do about this :-( I don't have any ideas about > > > > > > how to > > > > > > eliminate this overhead, so the only option I see is reverting the > > > > > > changes > > > > > > in heap_insert. Unfortunately, that'd mean inserts into TOAST > > > > > > tables won't > > > > > > be frozen ... > > > > > > > > > > ISTM that the fundamental issue here is not that we acquire pins that > > > > > we > > > > > shouldn't, but that we do so at a much higher frequency than needed. > > > > > > > > > > It's probably too invasive for 14, but I think it might be worth > > > > > exploring > > > > > passing down a BulkInsertState in nodeModifyTable.c's > > > > > table_tuple_insert() iff > > > > > the input will be more than one row. > > > > > > > > > > And then add the vm buffer of the target page to BulkInsertState, so > > > > > that > > > > > hio.c can avoid re-pinning the buffer. > > > > > > > > > > > > > Yeah. The question still is what to do about 14, though. Shall we leave > > > > the > > > > code as it is now, or should we change it somehow? It seem a bit > > > > unfortunate > > > > that a COPY FREEZE optimization should negatively influence other (more) > > > > common use cases, so I guess we can't just keep the current code ... > > > > > > I'd suggest prototyping the use of BulkInsertState in nodeModifyTable.c > > > and see whether that fixes the regression. > > What Andres is suggesting (I think) is to modify ExecInsert() to pass a > valid bistate to table_tuple_insert, instead of just NULL, and store the > vmbuffer in it. Not sure how to identify when inserting more than just a > single row, though ...
Maybe this is relevant. https://commitfest.postgresql.org/33/2553/ | INSERT SELECT: BulkInsertState and table_multi_insert The biistate part is small - Simon requested to also use table_multi_insert, which makes the patch much bigger, and there's probably lots of restrictions I haven't even thought to check. This uses a GUC threshold for bulk insert, but I'm still not sure it's really problematic to use a biistate for a single row. /* Use bulk insert after a threshold number of tuples */ // XXX: maybe this should only be done if it's not a partitioned table or // if the partitions don't support miinfo, which uses its own bistates mtstate->ntuples++; if (mtstate->bistate == NULL && mtstate->ntuples > bulk_insert_ntuples && bulk_insert_ntuples >= 0) { elog(DEBUG1, "enabling bulk insert"); mtstate->bistate = GetBulkInsertState(); -- Justin
