Horton

Re: [Patch] ALTER SYSTEM READ ONLY

Amul Sul <sulamul@gmail.com>

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From: Amul Sul <sulamul@gmail.com>
To: tushar <tushar.ahuja@enterprisedb.com>
Cc: Robert Haas <robertmhaas@gmail.com>, Amit Kapila <amit.kapila16@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>
Date: 2020-06-26T04:41:41Z
Lists: pgsql-hackers 
On Wed, Jun 24, 2020 at 1:54 PM tushar <tushar.ahuja@enterprisedb.com> wrote:
>
> On 6/22/20 11:59 AM, Amul Sul wrote:
> > 2. Now skipping the startup checkpoint if the system is read-only mode, as
> > discussed [2].
>
> I am not able to perform pg_checksums o/p after shutting down my server
> in read only  mode .
>
> Steps -
>
> 1.initdb (./initdb -k -D data)
> 2.start the server(./pg_ctl -D data start)
> 3.connect to psql (./psql postgres)
> 4.Fire query (alter system read only;)
> 5.shutdown the server(./pg_ctl -D data stop)
> 6.pg_checksums
>
> [edb@tushar-ldap-docker bin]$ ./pg_checksums -D data
> pg_checksums: error: cluster must be shut down
> [edb@tushar-ldap-docker bin]$
>
> Result - (when server is not in read only)
>
> [edb@tushar-ldap-docker bin]$ ./pg_checksums -D data
> Checksum operation completed
> Files scanned:  916
> Blocks scanned: 2976
> Bad checksums:  0
> Data checksum version: 1
>
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).

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.