Horton

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

Ashutosh Sharma <ashu.coek88@gmail.com>

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From: Ashutosh Sharma <ashu.coek88@gmail.com>
To: Dilip Kumar <dilipbalaut@gmail.com>
Cc: Maciek Sakrejda <m.sakrejda@gmail.com>, Robert Haas <robertmhaas@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: 2022-02-22T14:57:12Z
Lists: pgsql-hackers 
I'm not sure about the current status, but found it while playing
around with the latest changes a bit, so thought of sharing it here.

+      <varlistentry>
+       <term><replaceable class="parameter">strategy</replaceable></term>
+       <listitem>
+        <para>
+         This is used for copying the database directory.  Currently, we have
+         two strategies the <literal>WAL_LOG_BLOCK</literal> and the

Isn't it wal_log instead of wal_log_block?

I think when users input wrong strategy with createdb command, we
should provide a hint message showing allowed values for strategy
types along with an error message. This will be helpful for the users.

On Tue, Feb 15, 2022 at 5:19 PM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Tue, Feb 15, 2022 at 2:01 AM Maciek Sakrejda <m.sakrejda@gmail.com> wrote:
> >
> Here is the updated version of the patch, the changes are 1) Fixed
> review comments given by Robert and one open comment from Ashutosh.
> 2) Preserved the old create db method. 3) As agreed upthread for now
> we are using the new strategy only for createdb not for movedb so I
> have removed the changes in ForgetDatabaseSyncRequests() and
> DropDatabaseBuffers().  3) Provided a database creation strategy
> option as of now I have kept it as below.
>
> CREATE DATABASE ... WITH (STRATEGY = WAL_LOG);      -- default if
> option is omitted
> CREATE DATABASE ... WITH (STRATEGY = FILE_COPY);
>
> I have updated the document but I was not sure how much internal
> information to be exposed to the user so I will work on that based on
> feedback from others.
>
> --
> Regards,
> Dilip Kumar
> EnterpriseDB: 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.