Horton

Re: [Proposal] Fully WAL logged CREATE DATABASE - No Checkpoints

Andres Freund <andres@anarazel.de>

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From: Andres Freund <andres@anarazel.de>
To: Tom Lane <tgl@sss.pgh.pa.us>
Cc: Robert Haas <robertmhaas@gmail.com>, Dilip Kumar <dilipbalaut@gmail.com>, Justin Pryzby <pryzby@telsasoft.com>, Ashutosh Sharma <ashu.coek88@gmail.com>, Maciek Sakrejda <m.sakrejda@gmail.com>, Bruce Momjian <bruce@momjian.us>, Alvaro Herrera <alvherre@alvh.no-ip.org>, Andrew Dunstan <andrew@dunslane.net>, Heikki Linnakangas <hlinnaka@iki.fi>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>, Thomas Munro <thomas.munro@gmail.com>
Date: 2022-08-05T00:06:04Z
Lists: pgsql-hackers 
Hi, 

On August 4, 2022 4:20:16 PM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>Yeah, the assumption that P_NEW would automatically match the source block
>was making me itchy too.  An explicit test-and-elog seems worth the
>cycles.

Is there a good reason to rely on P_NEW at all? Both from an efficiency and robustness POV it seems like it'd be better to use smgrextend to bulk extend just after smgrcreate() and then fill s_b u using RBM_ZERO (or whatever it is called).  That bulk smgrextend would later be a good point to use fallocate so the FS can immediately size the file correctly, without a lot of pointless writes of zeroes. 

Andres
-- 
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Commits

  1. When using the WAL-logged CREATE DATABASE strategy, bulk extend.

  2. Avoid using a fake relcache entry to own an SmgrRelation.

  3. Fix data-corruption hazard in WAL-logged CREATE DATABASE.

  4. initdb: When running CREATE DATABASE, use STRATEGY = WAL_COPY.

  5. Simplify a needlessly-complicated regular expression.

  6. In 020_createdb.pl, change order of command-line arguments.

  7. Add new block-by-block strategy for CREATE DATABASE.

  8. Fix replay of create database records on standby

  9. Refactor code for reading and writing relation map files.

  10. Replace RelationOpenSmgr() with RelationGetSmgr().

  11. Refactor the fsync queue for wider use.