Horton

Re: snapbuild woes

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Petr Jelinek <petr.jelinek@2ndquadrant.com>
Cc: PostgreSQL-development <pgsql-hackers@postgresql.org>, Erik Rijkers <er@xs4all.nl>, Robert Haas <robertmhaas@gmail.com>, Craig Ringer <craig@2ndquadrant.com>
Date: 2017-05-01T01:35:29Z
Lists: pgsql-hackers

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On 2017-04-30 17:59:21 -0700, Andres Freund wrote:
> ISTM, we need a xip_status array in SnapBuild->running.  Then, whenever
> a xl_running_xacts is encountered while builder->running.xcnt > 0, loop
> for i in 0 .. xcnt_space, and end SnapBuildEndTxn() if xip_status[i] but
> the xid is not xl_running_xacts?  Does that make sense?

A hasty implementation, untested besides check-world, of that approach
is attached.  I'm going out for dinner now, will subject it to mean
things afterwards.

Needs more testing, comment and commit message policing.  But I think
the idea is sound?

- Andres

Commits

  1. Fix thinko introduced in 2bef06d516460 et al.

  2. Avoid superfluous work for commits during logical slot creation.

  3. Fix race condition leading to hanging logical slot creation.

  4. Don't use on-disk snapshots for exported logical decoding snapshot.

  5. Preserve required !catalog tuples while computing initial decoding snapshot.