From: Nathan Bossart <nathandbossart@gmail.com>
To: Robert Haas <robertmhaas@gmail.com>
Cc: Jeff Davis <pgsql@j-davis.com>
Cc: pgsql-hackers@postgresql.org
Subject: Re: optimizing pg_upgrade's once-in-each-database steps
Date: Mon, 1 Jul 2024 15:00:53 -0500
Message-ID: <ZoMK9ZhOsWEKqxlM@nathan> (raw)
In-Reply-To: <CA+TgmoaBof36-ZuRWtu=+8rnhGTNQFFGNcmVB0x3aQawfc_JxA@mail.gmail.com>
References: <20240516211638.GA1688936@nathanxps13>
<3b97ab8e295ec3db22baa2dfdd49073449ae1696.camel@j-davis.com>
<20240517012408.GA1691322@nathanxps13>
<ZoMHsBasBy8LqkEU@nathan>
<CA+TgmoaBof36-ZuRWtu=+8rnhGTNQFFGNcmVB0x3aQawfc_JxA@mail.gmail.com>
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
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To: pgsql-hackers@postgresql.org
Cc: nathandbossart@gmail.com, robertmhaas@gmail.com, pgsql@j-davis.com
Subject: Re: optimizing pg_upgrade's once-in-each-database steps
In-Reply-To: <ZoMK9ZhOsWEKqxlM@nathan>
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