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Re: logical decoding - GetOldestXmin

Robert Haas <robertmhaas@gmail.com>

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From: Robert Haas <robertmhaas@gmail.com>
To: Andres Freund <andres@2ndquadrant.com>
Cc: Peter Geoghegan <peter@2ndquadrant.com>, pgsql-hackers@postgresql.org
Date: 2012-12-13T22:29:06Z
Lists: pgsql-hackers 
On Thu, Dec 13, 2012 at 3:03 PM, Andres Freund <andres@2ndquadrant.com> wrote:
> It moves a computation of the sort of:
>
> result -= vacuum_defer_cleanup_age;
> if (!TransactionIdIsNormal(result))
>    result = FirstNormalTransactionId;
>
> inside ProcArrayLock. But I can't really imagine that to be relevant...

I can.  Go look at some of the 9.2 optimizations around
GetSnapshotData().  Those made a BIG difference under heavy
concurrency and they were definitely micro-optimization.  For example,
the introduction of NormalTransactionIdPrecedes() was shockingly
effective.

-- 
Robert Haas
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. Background worker processes

  2. Rearrange storage of data in xl_running_xacts.

  3. Basic binary heap implementation.

  4. Embedded list interface

  5. Refactor xlog.c to create src/backend/postmaster/startup.c