Horton

Re: [HACKERS] WAL logging problem in 9.4.3?

Peter Eisentraut <peter.eisentraut@2ndquadrant.com>

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From: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>
To: Robert Haas <robertmhaas@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>
Cc: Noah Misch <noah@leadboat.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Dmitry Dolgov <9erthalion6@gmail.com>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, hlinnaka <hlinnaka@iki.fi>, Michael Paquier <michael@paquier.xyz>
Date: 2019-11-22T12:21:31Z
Lists: pgsql-hackers 
On 2019-11-05 22:16, Robert Haas wrote:
> First, I'd like to restate my understanding of the problem just to see
> whether I've got the right idea and whether we're all on the same
> page. When wal_level=minimal, we sometimes try to skip WAL logging on
> newly-created relations in favor of fsync-ing the relation at commit
> time.

How useful is this behavior, relative to all the effort required?

Even if the benefit is significant, how many users can accept running 
with wal_level=minimal and thus without replication or efficient backups?

Is there perhaps an alternative approach involving unlogged tables to 
get a similar performance benefit?

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

Commits

  1. Add perl2host call missing from a new test file.

  2. Skip WAL for new relfilenodes, under wal_level=minimal.

  3. Revert "Skip WAL for new relfilenodes, under wal_level=minimal."

  4. Back-patch log_newpage_range().

  5. During heap rebuild, lock any TOAST index until end of transaction.

  6. In log_newpage_range(), heed forkNum and page_std arguments.

  7. Back-patch src/test/recovery and PostgresNode from 9.6 to 9.5.

  8. Reduce pg_ctl's reaction time when waiting for postmaster start/stop.

  9. Accelerate end-of-transaction dropping of relations

  10. Redesign the planner's handling of index-descent cost estimation.

  11. Make TRUNCATE do truncate-in-place when processing a relation that was created