Horton

Re: [HACKERS] WAL logging problem in 9.4.3?

Michael Paquier <michael@paquier.xyz>

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From: Michael Paquier <michael@paquier.xyz>
To: Noah Misch <noah@leadboat.com>
Cc: Peter Eisentraut <peter.eisentraut@2ndquadrant.com>, Robert Haas <robertmhaas@gmail.com>, Kyotaro Horiguchi <horikyota.ntt@gmail.com>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Dmitry Dolgov <9erthalion6@gmail.com>, Andrew Dunstan <andrew.dunstan@2ndquadrant.com>, hlinnaka <hlinnaka@iki.fi>
Date: 2019-11-24T12:53:16Z
Lists: pgsql-hackers 
On Sat, Nov 23, 2019 at 11:35:09AM -0500, Noah Misch wrote:
> That longstanding optimization is too useful to remove, but likely not useful
> enough to add today if we didn't already have it.  The initial-data-load use
> case remains plausible.  I can also imagine using wal_level=minimal for data
> warehouse applications where one can quickly rebuild from the authoritative
> data.

I can easily imagine cases where a user would like to use the benefit
of the optimization for an initial data load, and afterwards update
wal_level to replica so as they avoid the initial WAL burst which
serves no real purpose.  So the first argument is pretty strong IMO,
the second much less.
--
Michael

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