Horton

Re: Speed up Clog Access by increasing CLOG buffers

Amit Kapila <amit.kapila16@gmail.com>

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From: Amit Kapila <amit.kapila16@gmail.com>
To: Andres Freund <andres@anarazel.de>
Cc: David Steele <david@pgmasters.net>, Robert Haas <robertmhaas@gmail.com>, Thom Brown <thom@linux.com>, Simon Riggs <simon@2ndquadrant.com>, Jesper Pedersen <jesper.pedersen@redhat.com>, pgsql-hackers <pgsql-hackers@postgresql.org>
Date: 2016-03-22T14:36:13Z
Lists: pgsql-hackers 
On Tue, Mar 22, 2016 at 6:29 PM, Andres Freund <andres@anarazel.de> wrote:
>
> On 2016-03-22 18:19:48 +0530, Amit Kapila wrote:
> > > I'm actually rather unconvinced that it's all that common that all
> > > subtransactions are on one page. If you have concurrency - otherwise
> > > there'd be not much point in this patch - they'll usually be heavily
> > > interleaved, no?  You can argue that you don't care about subxacts,
> > > because they're more often used in less concurrent scenarios, but if
> > > that's the argument, it should actually be made.
> > >
> >
> > Note, that we are doing it only when a transaction has less than equal
to
> > 64 sub transactions.
>
> So?
>

They should fall on one page, unless they are heavily interleaved as
pointed by you.  I think either subtransactions are present or not, this
patch won't help for bigger transactions.

I will address your other review comments and send an updated patch.

Thanks for the review.


With Regards,
Amit Kapila.
EnterpriseDB: http://www.enterprisedb.com

Commits

  1. Use group updates when setting transaction status in clog.

  2. Improve 64bit atomics support.

  3. Add ProcArrayGroupUpdate wait event.

  4. Make the different Unix-y semaphore implementations ABI-compatible.

  5. Fix broken ALTER INDEX documentation

  6. Code and docs review for commit 3187d6de0e5a9e805b27c48437897e8c39071d45.

  7. Partition the freelist for shared dynahash tables.

  8. Correct StartupSUBTRANS for page wraparound

  9. Make idle backends exit if the postmaster dies.

  10. contrib/sslinfo: add ssl_extension_info SRF

  11. Reduce ProcArrayLock contention by removing backends in batches.

  12. Fix `make installcheck` for serializable transactions.

  13. Lockless StrategyGetBuffer clock sweep hot path.

  14. Reduce sinval synchronization overhead.