Horton

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

Robert Haas <robertmhaas@gmail.com>

View thread View on postgr.es
From: Robert Haas <robertmhaas@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: 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: 2022-03-14T15:33:25Z
Lists: pgsql-hackers 
On Sat, Mar 12, 2022 at 12:36 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> So here my stand is that we need to drop database buffers and remove
> pending sync requests because we are deleting underlying files and if
> we do not do that in some extreme cases then there is no need to drop
> the buffers or remove the pending sync request and the worst
> consequences would be waste of disk space.

Hmm, I guess you're right.

On Mon, Mar 14, 2022 at 7:51 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> - Removed unused structure and macro because we are using the same WAL
> for copying the database using the old method or creating the
> directory and version files for the new method.  Do you think we
> should introduce a new WAL for that instead of using the same?

I think it would make sense to have two different WAL records e.g.
XLOG_DBASE_CREATE_WAL_LOG and XLOG_DBASE_CREATE_FILE_COPY. Then it's
easy to see how this could be generalized to other strategies in the
future.

-- 
Robert Haas
EDB: http://www.enterprisedb.com

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.