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: Alvaro Herrera <alvherre@alvh.no-ip.org>
Cc: Robert Haas <robertmhaas@gmail.com>, Andrew Dunstan <andrew@dunslane.net>, Heikki Linnakangas <hlinnaka@iki.fi>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Date: 2022-02-14T16:25:51Z
Lists: pgsql-hackers 
On Sun, Feb 13, 2022 at 10:12 AM Dilip Kumar <dilipbalaut@gmail.com> wrote:
>
> On Sat, Feb 12, 2022 at 2:38 AM Alvaro Herrera <alvherre@alvh.no-ip.org> wrote:

> > It seems you're thinking deciding what to do based on an option that
> > gets a boolean argument.  But what about making the argument be an enum?
> > For example
> >
> > CREATE DATABASE ... WITH (STRATEGY = LOG);      -- default if option is omitted
> > CREATE DATABASE ... WITH (STRATEGY = CHECKPOINT);
> >
> > So the user has to think about it in terms of some strategy to choose,
> > rather than enabling or disabling some flag with nontrivial
> > implications.
>
>
> Yeah I think being explicit about giving the strategy to the user
> looks like a better option.  Now they can choose whether they want it
> to create using WAL log or using CHECKPOINT.  Otherwise, if we give a
> flag then we will have to give an explanation that if they choose not
> to WAL log then we will have to do a checkpoint internally.  So I
> think giving LOG vs CHECKPOINT as an explicit option looks better to
> me.

So do we have consensus to use (STRATEGY = LOG/CHECKPOINT or do we
think that keeping it bool i.e. Is LOG_COPIED_BLOCKS a better option?
Once we have consensus on this I will make this change and
documentation as well along with the other changes suggested by
Robert.

-- 
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.