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Re: increasing the default WAL segment size

Jeff Janes <jeff.janes@gmail.com>

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From: Jeff Janes <jeff.janes@gmail.com>
To: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
Cc: David Steele <david@pgmasters.net>, Stephen Frost <sfrost@snowman.net>, Robert Haas <robertmhaas@gmail.com>, Beena Emerson <memissemerson@gmail.com>, 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: 2017-03-24T01:47:45Z
Lists: pgsql-hackers 
On Thu, Mar 23, 2017 at 1:45 PM, Peter Eisentraut <
peter.eisentraut@2ndquadrant.com> wrote:

> On 3/22/17 17:33, David Steele wrote:
>
> > and I doubt that most tool writers would be quick to
> > add support for a feature that very few people (if any) use.
>
> I'm not one of those tool writers, although I have written my share of
> DBA scripts over the years, but I wonder why those tools would really
> care.  They are handed files with predetermined names to archive, and
> for restore files with predetermined names are requested back from them.
>  What else do they need?  If something is missing that requires them to
> parse file names, then maybe that should be added.
>


I have a pg_restore which predicts the file 5 files ahead of the one it was
asked for, and initiates a pre-fetch and decompression of it. Then it
delivers the file it was asked for, either by pulling it out of the
pre-staging area set up by the N-5th invocation, or by going directly to
the archive to get it.  This speeds up play-back dramatically when the
files are stored compressed and non-local.

That is why I need to know how the files are numbered.  I don't think that
that makes much of a difference, though.  Any change is going to break
that, no matter which change.  Then I'll fix it.

If we are going to break it, I'd prefer to just do away with the 'segment'
thing altogether.  You have timelines, and you have files.  That's it.

Cheers,

Jeff

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.