At Wed, 9 Dec 2020 16:27:30 +0530, Amit Kapila <amit.kapil...@gmail.com> wrote in > On Wed, Dec 9, 2020 at 6:32 AM Kyotaro Horiguchi > <horikyota....@gmail.com> wrote: > > > > At Tue, 8 Dec 2020 16:28:41 +0530, Amit Kapila <amit.kapil...@gmail.com> > > wrote in > > > On Tue, Dec 8, 2020 at 12:13 PM tsunakawa.ta...@fujitsu.com > > > <tsunakawa.ta...@fujitsu.com> wrote: > > > > > > > > From: Jamison, Kirk/ジャミソン カーク <k.jami...@fujitsu.com> > > > > > Because one of the rel's cached value was false, it forced the > > > > > full-scan path for TRUNCATE. > > > > > Is there a possible workaround for this? > > > > > > > > Hmm, the other two relfilenodes are for the TOAST table and index of > > > > the target table. I think the INSERT didn't access those TOAST > > > > relfilenodes because the inserted data was stored in the main storage. > > > > But TRUNCATE always truncates all the three relfilenodes. So, the > > > > standby had not opened the relfilenode for the TOAST stuff or cached > > > > its size when replaying the TRUNCATE. > > > > > > > > I'm afraid this is more common than we can ignore and accept the slow > > > > traditional path, but I don't think of a good idea to use the cached > > > > flag. > > > > > > > > > > I also can't think of a way to use an optimized path for such cases > > > but I don't agree with your comment on if it is common enough that we > > > leave this optimization entirely for the truncate path. > > > > Mmm. At least btree doesn't need to call smgrnblocks except at > > expansion, so we cannot get to the optimized path in major cases of > > truncation involving btree (and/or maybe other indexes). > > > > AFAICS, btree insert should call smgrnblocks via > btree_xlog_insert->XLogReadBufferForRedo->XLogReadBufferForRedoExtended->XLogReadBufferExtended->smgrnblocks. > Similarly delete should also call smgrnblocks. Can you be bit more > specific related to the btree case you have in mind?
Oh, sorry. I wrongly looked to non-recovery path. smgrnblocks is called during buffer loading while recovery. So, smgrnblock is called for indexes if any update happens on the heap relation. regards. -- Kyotaro Horiguchi NTT Open Source Software Center
