Date: Tue, 19 Jul 2022 13:13:07 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Bruce Momjian <bruce@momjian.us>
Cc: pgsql-hackers@postgresql.org
Subject: Re: First draft of the PG 15 release notes
Message-ID: <20220719181307.GG12702@telsasoft.com>
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On Tue, Jul 19, 2022 at 01:24:30PM -0400, Bruce Momjian wrote:
> > > Remove pg_dump's --no-synchronized-snapshots option since all supported server versions support synchronized snapshots (Tom Lane)
> > 
> > It'd be better to put that after the note about dropping support for upgrading
> > clusters older than v9.2 in psql/pg_dump/pg_upgrade.
> 
> Well, I put the --no-synchronized-snapshots item in incompatibilities
> since it is a user-visible change that might require script adjustments.
> However, I put the limit of pg_dump to 9.2 and greater into the pg_dump
> section.  Are you suggesting I move the--no-synchronized-snapshots item
> down there?  That doesn't match with the way I have listed other
> incompatibilities so I am resistant to do that.

I'd rather see the "limit support to v9.2" be moved or added to the
"incompatibilities" section, maybe with "remove --no-synchronized-snapshots"
as a secondary sentence.

> > > 0. Add support for LZ4 and Zstandard compression of server-side base backups (Jeevan Ladhe, Robert Haas)
> > > 1. Allow pg_basebackup to use LZ4 and Zstandard compression on server-side base backup files (Dipesh Pandit, Jeevan Ladhe)
> > > 2. Allow pg_basebackup's --compress option to control the compression method and options (Michael Paquier, Robert Haas)
> > >    New options include server-gzip (gzip on the server), client-gzip (same as gzip).
> > > 3. Allow pg_basebackup to compress on the server side and decompress on the client side before storage (Dipesh Pandit)
> > >    This is accomplished by specifying compression on the server side and plain output format.
> > 
> > I still think these expose the incremental development rather than the
> > user-facing change.
> 
> > 1. It seems wrong to say "server-side" since client-side compression with
> > LZ4/zstd is also supported.
> 
> Agreed.  I changed it to:
> 
>        Allow pg_basebackup to do LZ4 and Zstandard server-side compression
>        on base backup files (Dipesh Pandit, Jeevan Ladhe)

This still misses the point that those compression algs are also supported on
the client side, so it seems misleading to mention "server-side" support.

> > > Allow custom scan provders to indicate if they support projections (Sven Klemm)
> > > The default is now that custom scan providers can't support projections, so they need to be updated for this release.
> > 
> > Per the commit message, they don't "need" to be updated.
> > I think this should say "The default now assumes that a custom scan provider
> > does not support projections; to retain optimal performance, they should be
> > updated to indicate whether that's supported.
> 
> Okay, I went with this text:
> 
>       The default is now that custom scan providers are assumed to not
>       support projections;  those that do need to be updated for this
>       release.

I'd say "those that do *will need to be updated" otherwise the sentence can
sound like it means "those that need to be updated [will] ..."

Thanks,
-- 
Justin