Horton

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

Tom Lane <tgl@sss.pgh.pa.us>

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From: Tom Lane <tgl@sss.pgh.pa.us>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Andres Freund <andres@anarazel.de>, Justin Pryzby <pryzby@telsasoft.com>, Robert Haas <robertmhaas@gmail.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>
Date: 2022-08-06T16:06:44Z
Lists: pgsql-hackers 
Dilip Kumar <dilipbalaut@gmail.com> writes:
> On Fri, Aug 5, 2022 at 10:43 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>> Yeah maybe it is not necessary to close as these unowned smgr will
>> automatically get closed on the transaction end.

I do not think this is a great idea for the per-relation smgrs created
during RelationCopyStorageUsingBuffer.  Yeah, they'll be mopped up at
transaction end, but that doesn't mean that creating possibly tens of
thousands of transient smgrs isn't going to cause performance issues.

I think RelationCopyStorageUsingBuffer needs to open and then close
the smgrs it uses, which means that ReadBufferWithoutRelcache is not the
appropriate API for it to use, either; need to go down another level.

			regards, tom lane

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.