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>, Robert Haas <robertmhaas@gmail.com>
Cc: 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: 2022-08-04T23:59:22Z
Lists: pgsql-hackers 
Hi, 

On August 4, 2022 4:11:13 PM PDT, Tom Lane <tgl@sss.pgh.pa.us> wrote:
>I wrote:
>> And while I'm piling on, how is this bit in RelationCopyStorageUsingBuffer
>> not completely broken?
>
>[pile^2]  Also, what is the rationale for locking the target buffer
>but not the source buffer?  That seems pretty hard to justify from
>here, even granting the assumption that we don't expect any other
>processes to be interested in these buffers (which I don't grant,
>because checkpointer).

I'm not arguing it's good or should stay that way, but it's probably okayish that checkpointer / bgwriter have access, given that they will never modify buffers. They just take a lock to prevent concurrent modifications, which RelationCopyStorageUsingBuffer hopefully doesn't do. 

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.