Horton

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

Dilip Kumar <dilipbalaut@gmail.com>

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From: Dilip Kumar <dilipbalaut@gmail.com>
To: Robert Haas <robertmhaas@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: 2022-03-23T08:36:41Z
Lists: pgsql-hackers

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On Tue, Mar 22, 2022 at 8:53 PM Robert Haas <robertmhaas@gmail.com> wrote:
>
> On Tue, Mar 22, 2022 at 5:00 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
> > In my previous patch mistakenly I used src_dboid instead of
> > dest_dboid.  Fixed in this version.  For destination db I have used
> > lock mode as  AccessSharedLock.  Logically if we see access wise we
> > don't want anyone else to be accessing that db but that is anyway
> > protected because it is not visible to anyone else.  So I think
> > AccessSharedLock should be correct here because we are just taking
> > this lock because we are accessing pages in shared buffers from this
> > database's relations.
>
> Here's my worked-over version of your previous patch. I haven't tried
> to incorporate your incremental patch that you just posted.

Thanks for working on the comments.  Please find the updated version
which include below changes
- Worked on the XXX comments added by you.
- Added database level lock for the target database as well.
- Used fake relcache and removed direct access to the smgr, I think it
was not really necessary in
ScanSourceDatabasePgClass() because we are using it for a very short
period of time but still I have changed it, let me know if you think
that it is unneccessary to create the fake relcache here.
- Removed extra space in createdb.c and fixed test case.

-- 
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.