On Wed, Jun 12, 2024 at 6:43 AM Kyotaro Horiguchi <horikyota....@gmail.com> wrote: > > At Tue, 11 Jun 2024 14:27:28 +0530, Amit Kapila <amit.kapil...@gmail.com> > wrote in > > On Tue, Jun 11, 2024 at 12:34 PM Kyotaro Horiguchi > > <horikyota....@gmail.com> wrote: > > > > > > At Tue, 11 Jun 2024 11:32:12 +0530, Amit Kapila <amit.kapil...@gmail.com> > > > wrote in > > > > Sorry, it is not clear to me why we failed to flush the last > > > > continuation record in logical walsender? I see that we try to flush > > > > the WAL after receiving got_STOPPING in WalSndWaitForWal(), why is > > > > that not sufficient? > > > > > > It seems that, it uses XLogBackgroundFlush(), which does not guarantee > > > flushing WAL until the end. > > > > > > > What would it take to ensure the same? I am trying to explore this > > path because currently logical WALSender sends any outstanding logs up > > to the shutdown checkpoint record (i.e., the latest record) and waits > > for them to be replicated to the standby before exit. Please take a > > look at the comments where we call WalSndDone(). The fix you are > > proposing will break that guarantee. > > Shutdown checkpoint is performed after the walsender completed > termination since 086221cf6b, >
Yeah, but the commit you quoted later reverted by commit 703f148e98 and committed again as c6c3334364. > aiming to prevent walsenders from > generating competing WAL (by, for example, CREATE_REPLICATION_SLOT) > records with the shutdown checkpoint. Thus, it seems that the > walsender cannot see the shutdown record, > This is true of logical walsender. The physical walsender do send shutdown checkpoint record before getting terminated. > and a certain amount of > bytes before it, as the walsender appears to have relied on the > checkpoint flushing its record, rather than on XLogBackgroundFlush(). > > If we approve of the walsender being terminated before the shutdown > checkpoint, we need to "fix" the comment, then provide a function to > ensure the synchronization of WAL records. > Which comment do you want to fix? > I'll consider this direction for a while. > Okay, thanks. -- With Regards, Amit Kapila.