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Re: increasing the default WAL segment size

Beena Emerson <memissemerson@gmail.com>

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From: Beena Emerson <memissemerson@gmail.com>
To: Michael Paquier <michael.paquier@gmail.com>
Cc: PostgreSQL mailing lists <pgsql-hackers@postgresql.org>
Date: 2017-01-06T09:32:19Z
Lists: pgsql-hackers 
On Fri, Jan 6, 2017 at 11:36 AM, Michael Paquier <michael.paquier@gmail.com>
wrote:

> On Thu, Jan 5, 2017 at 8:39 PM, Beena Emerson <memissemerson@gmail.com>
> wrote:
> > On Tue, Jan 3, 2017 at 5:46 PM, Michael Paquier <
> michael.paquier@gmail.com>
> > wrote:
> >> Actually, why not just having an equivalent of the SQL
> >> command and be able to query parameter values?
> >
> > This patch only needed the wal_segment_size and hence I made this
> specific
> > command.
> > How often and why would we need other parameter values in the replication
> > connection?
> > Making it a more general command to fetch any parameter can be a separate
> > topic. If it gets consensus, maybe it could be done and used here.
>
> I concur that for this patch it may not be necessary. But let's not
> narrow us in a corner when designing things. Being able to query the
> value of parameters is something that I think is actually useful for
> cases where custom GUCs are loaded on the server's
> shared_preload_libraries to do validation checks (one case is a
> logical decoder on backend, with streaming receiver as client
> expecting the logical decoder to do a minimum). This can allow a
> client to do checks only using a replication stream. Another case that
> I have in mind is for utilities like pg_rewind, we have been
> discussing about being able to not need a superuser when querying the
> target server. Having such a command would allow for example pg_rewind
> to do a 'SHOW full_page_writes' without the need of an extra
> connection.
>
>
I see the point. I will change the SHOW_WAL_SEGSZ to a general SHOW command
in the next version of the patch.

Thank you,

Beena Emerson

Have a Great Day!

Commits

Same data as JSON: GET /api/v1/messages/:b64id/commits the thread's linked commits as JSON, with link sources. API reference →

  1. Make WAL segment size configurable at initdb time.

  2. Perform only one ReadControlFile() during startup.

  3. Introduce BYTES unit for GUCs.

  4. Remove useless duplicate inclusions of system header files.

  5. Refactor other replication commands to use DestRemoteSimple.

  6. Add a SHOW command to the replication command language.

  7. Add a new DestReceiver for printing tuples without catalog access.

  8. Support fls().

  9. Extend yesterday's patch making BLCKSZ and RELSEG_SIZE configurable to also

  10. Commit the reasonably uncontroversial parts of J.R. Nield's PITR patch, to

  11. XLOG (also known as WAL -:)) Bootstrap/Startup/Shutdown.

  12. Transaction log manager core code.