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: 2022-03-11T18:10:48Z
Lists: pgsql-hackers 
On Fri, Mar 11, 2022 at 5:21 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> Changes, 1) it take Robert's patch as first refactoring patch 2)
> Rebase other new relmapper apis on top of that in 0002 3) Some code
> refactoring in main patch 0005 and also one problem fix, earlier in
> wal log method I have removed ForceSyncCommit(), but IMHO that is
> equally valid whether we use file_copy or wal_log because in both
> cases we are creating the disk files.  4) Support strategy in createdb
> tool and add test case as part of 0006.

I don't think you've adequately considered temporary relations here.
It seems to be that ReadBufferWithoutRelcache() could not be safe on a
temprel, because we'd need a BackendId to access the underlying
storage. So I think that ReadBufferWithoutRelcache can only accept
unlogged or permanent, and maybe the argument ought to be a Boolean
instead of a relpersistence value. I thought that this problem might
be only cosmetic, but I checked the code that actually does the copy,
and there's no filter there on relpersistence either. And I think
there should be.


-- 
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.