On Fri, Feb 25, 2022 at 11:17 PM Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Sat, Feb 26, 2022 at 3:01 AM Melanie Plageman > <melanieplage...@gmail.com> wrote: > > > > Since _hash_alloc_buckets() WAL-logs the last page of the > > splitpoint, is it safe to skip the smgrimmedsync()? What if the last > > page of the splitpoint doesn't end up having any tuples added to it > > during the index build and the redo pointer is moved past the WAL for > > this page and then later there is a crash sometime before this page > > makes it to permanent storage. Does it matter that this page is lost? If > > not, then why bother WAL-logging it? > > > > I think we don't care if the page is lost before we update the > meta-page in the caller because we will try to reallocate in that > case. But we do care after meta page update (having the updated > information about this extension via different masks) in which case we > won't lose this last page because it would have registered the sync > request for it via sgmrextend before meta page update.
and could it happen that during smgrextend() for the last page, a checkpoint starts and finishes between FileWrite() and register_dirty_segment(), then index build finishes, and then a crash occurs before another checkpoint completes the pending fsync for that last page?
