Horton

Re: [Patch] ALTER SYSTEM READ ONLY

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Amul Sul <sulamul@gmail.com>
Cc: tushar <tushar.ahuja@enterprisedb.com>, Robert Haas <robertmhaas@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2020-06-26T09:59:21Z
Lists: pgsql-hackers 
On Fri, Jun 26, 2020 at 10:11:41AM +0530, Amul Sul wrote:
> I think that's expected since the server isn't clean shutdown, similar error can
> be seen with any server which has been shutdown in immediate mode
> (pg_clt -D data_dir -m i).

Any operation working on on-disk relation blocks needs to have a
consistent state, and a clean shutdown gives this guarantee thanks to
the shutdown checkpoint (see also pg_rewind).  There are two states in
the control file, shutdown for a primary and shutdown while in
recovery to cover that.  So if you stop the server cleanly but fail to
see a proper state with pg_checksums, it seems to me that the proposed
patch does not handle correctly the state of the cluster in the
control file at shutdown.  That's not good.
--
Michael

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.