Horton

Re: optimizing pg_upgrade's once-in-each-database steps

Nathan Bossart <nathandbossart@gmail.com>

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From: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Jeff Davis <pgsql@j-davis.com>, pgsql-hackers@postgresql.org
Date: 2024-07-01T20:00:53Z
Lists: pgsql-hackers 
On Mon, Jul 01, 2024 at 03:58:16PM -0400, Robert Haas wrote:
> On Mon, Jul 1, 2024 at 3:47 PM Nathan Bossart <nathandbossart@gmail.com> wrote:
>> 0001 introduces a new API for registering callbacks and running them in
>> parallel on all databases in the cluster.  This new system manages a set of
>> "slots" that follow a simple state machine to asynchronously establish a
>> connection and run the queries.  It uses system() to wait for these
>> asynchronous tasks to complete.  Users of this API only need to provide two
>> callbacks: one to return the query that should be run on each database and
>> another to process the results of that query.  If multiple queries are
>> required for each database, users can provide multiple sets of callbacks.
> 
> I do really like the idea of using asynchronous communication here. It
> should be significantly cheaper than using multiple processes or
> threads, and maybe less code, too. But I'm confused about why you
> would need or want to use system() to wait for asynchronous tasks to
> complete. Wouldn't it be something like select()?

Whoops, I meant to type "select()" there.  Sorry for the confusion.

-- 
nathan

Commits

  1. Introduce framework for parallelizing various pg_upgrade tasks.

  2. pg_upgrade: Parallelize WITH OIDS check.

  3. pg_upgrade: Parallelize contrib/isn check.

  4. pg_upgrade: Parallelize data type checks.

  5. pg_upgrade: Parallelize encoding conversion check.

  6. pg_upgrade: Parallelize incompatible polymorphics check.

  7. pg_upgrade: Parallelize postfix operator check.

  8. pg_upgrade: Parallelize retrieving extension updates.

  9. pg_upgrade: Parallelize retrieving loadable libraries.

  10. pg_upgrade: Parallelize retrieving relation information.

  11. pg_upgrade: Parallelize subscription check.

  12. pg_upgrade: Move live_check variable to user_opts.

  13. pg_upgrade: run all data type checks per connection