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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: Robert Haas <robertmhaas@gmail.com>
Cc: tushar <tushar.ahuja@enterprisedb.com>, Prabhat Sahu <prabhat.sahu@enterprisedb.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Jim Nasby <Jim.Nasby@bluetreble.com>, Kuntal Ghosh <kuntalghosh.2007@gmail.com>, Andres Freund <andres@anarazel.de>, "pgsql-hackers@postgresql.org" <pgsql-hackers@postgresql.org>
Date: 2017-03-17T06:08:56Z
Lists: pgsql-hackers 
Hello,

Thank you for your comments, I will post an updated patch soon.

On Fri, Mar 17, 2017 at 6:40 AM, Robert Haas <robertmhaas@gmail.com> wrote:
>
>
> +assign_wal_segment_size(int newval, void *extra)
>
> Why does a PGC_INTERNAL GUC need an assign hook?  I think the GUC
> should only be there to expose the value; it shouldn't have
> calculation logic associated with it.
>

The Checkpoint Segments and the UsableBytesInSegment had to be changed
depending on the value of  wal_segment_size set during initdb. I will
figure out another way to assign these values without using this
assign_hook.


> +               wal_segment_size = atoi(str_wal_segment_size);
>
> So, you're comfortable interpreting --wal-segsize=1TB or
> --wal-segsize=1GB as 1?  Implicitly, 1MB?
>

The option was intended to only accept values in MB as the original  config
--with-wal-segsize option, unfortunately, the patch does not throw error as
in the config option when the units are specified.

Error with config option --with-wal-segsize=1MB
configure: error: Invalid WAL segment size. Allowed values are
1,2,4,8,16,32,64.

Should we imitate this behaviour and just add a check to see if it only
contains numbers? or would it be better to allow the use of the units and
make appropriate code changes?

-- 
Thank you,

Beena Emerson

EnterpriseDB: http://www.enterprisedb.com
The Enterprise PostgreSQL Company

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.