Horton

Re: [Patch] ALTER SYSTEM READ ONLY

Amul Sul <sulamul@gmail.com>

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From: Amul Sul <sulamul@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Andres Freund <andres@anarazel.de>, Bharath Rupireddy <bharath.rupireddyforpostgres@gmail.com>, Ibrar Ahmed <ibrar.ahmad@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Prabhat Sahu <prabhat.sahu@enterprisedb.com>
Date: 2021-07-29T11:52:21Z
Lists: pgsql-hackers 
On Thu, Jul 29, 2021 at 4:47 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Wed, Jul 28, 2021 at 5:03 PM Amul Sul <sulamul@gmail.com> wrote:
> >
> > I was too worried about how I could miss that & after thinking more
> > about that, I realized that the operation for ArchiveRecoveryRequested
> > is never going to be skipped in the startup process and that never
> > left for the checkpoint process to do that later. That is the reason
> > that assert was added there.
> >
> > When ArchiveRecoveryRequested, the server will no longer be in
> > the wal prohibited mode, we implicitly change the state to
> > wal-permitted. Here is the snip from the 0003 patch:
> >
> > @@ -6614,13 +6629,30 @@ StartupXLOG(void)
> >   (errmsg("starting archive recovery")));
> >   }
> >
> > - /*
> > - * Take ownership of the wakeup latch if we're going to sleep during
> > - * recovery.
> > - */
> >   if (ArchiveRecoveryRequested)
> > + {
> > + /*
> > + * Take ownership of the wakeup latch if we're going to sleep during
> > + * recovery.
> > + */
> >   OwnLatch(&XLogCtl->recoveryWakeupLatch);
> >
> > + /*
> > + * Since archive recovery is requested, we cannot be in a wal prohibited
> > + * state.
> > + */
> > + if (ControlFile->wal_prohibited)
> > + {
> > + /* No need to hold ControlFileLock yet, we aren't up far enough */
> > + ControlFile->wal_prohibited = false;
> > + ControlFile->time = (pg_time_t) time(NULL);
> > + UpdateControlFile();
> > +
>
> Is there some reason why we are forcing 'wal_prohibited' to off if we
> are doing archive recovery?  It might have already been discussed, but
> I could not find it on a quick look into the thread.
>

Here is: https://postgr.es/m/CA+TgmoZ=CCTbAXxMTYZoGXEgqzOz9smkBWrDpsacpjvFcGCuaw@mail.gmail.com

Regards,
Amul

Commits

  1. Initialize variable to placate compiler.

  2. StartupXLOG: Don't repeatedly disable/enable local xlog insertion.

  3. StartupXLOG: Call CleanupAfterArchiveRecovery after XLogReportParameters.

  4. Postpone some end-of-recovery operations related to allowing WAL.

  5. Refactor some end-of-recovery code out of StartupXLOG().

  6. Re-enable contrib/bloom's TAP tests.

  7. Remove unnecessary call to ReadCheckpointRecord().

  8. Allow for error or refusal while absorbing a ProcSignalBarrier.

  9. Add comment to explain an unused function parameter

  10. Extend the ProcSignal mechanism to support barriers.

  11. At promotion, don't leave behind a partial segment on the old timeline.