Horton

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

Robert Haas <robertmhaas@gmail.com>

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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: 2022-03-10T16:48:16Z
Lists: pgsql-hackers

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On Thu, Mar 10, 2022 at 6:02 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> I have completely changed the logic for this refactoring.  Basically,
> write_relmap_file(), is already having parameters to control whether
> to write wal, send inval and we are already passing the dbpath.
> Instead of making a new function I just pass one additional parameter
> to this function itself about whether we are creating a new map or not
> and I think with that changes are very less and this looks cleaner to
> me.  Similarly for load_relmap_file() also I just had to pass the
> dbpath and memory for destination map.  Please have a look and let me
> know your thoughts.

It's not terrible, but how about something like the attached instead?
I think this has the effect of reducing the number of cases that the
low-level code needs to know about from 2 to 1, instead of making it
go up from 2 to 3.

> I think we should also write the test cases for create database
> strategy.  But I do not see any test case for create database for
> testing the existing options.  So I am wondering whether we should add
> the test case only for the new option we are providing or we should
> create a  separate path which tests the new option as well as the
> existing options.

FWIW, src/bin/scripts/t/020_createdb.pl does a little bit of testing
of this kind.

-- 
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.