Date: Wed, 12 Apr 2023 17:52:40 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Michael Paquier <michael@paquier.xyz>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>, gkokolatos@pm.me,
	shiy.fnst@fujitsu.com, pgsql-hackers@lists.postgresql.org,
	Rachel Heaton <rachelmheaton@gmail.com>
Subject: Re: Add LZ4 compression in pg_dump
Message-ID: <ZDc2OBeMYbhmDEYl@telsasoft.com>
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On Thu, Apr 13, 2023 at 07:23:48AM +0900, Michael Paquier wrote:
> On Tue, Apr 11, 2023 at 08:19:59PM -0500, Justin Pryzby wrote:
> > On Wed, Apr 12, 2023 at 10:07:08AM +0900, Michael Paquier wrote:
> >> Yes, this comment gives no value as it stands.  I would be tempted to
> >> follow the suggestion to group the whole code block in a single ifdef,
> >> including the check, and remove this comment.  Like the attached
> >> perhaps?
> > 
> > +1
> 
> Let me try this one again, as the previous patch would cause a warning
> under --without:-zlib as user_compression_defined would be unused.  We
> could do something like the attached instead.  It means doing twice
> parse_compress_specification() for the non-zlib path, still we are
> already doing so for the zlib path.
> 
> If there are other ideas, feel free.

I don't think you need to call parse_compress_specification(NONE).
As you wrote it, if zlib is unavailable, there's no parse(NONE) call,
even for directory and custom formats.  And there's no parse(NONE) call
for plan format when zlib is available.

The old way had preprocessor #if around both the "if" and "else" - is
that what you meant ?

If you don't insist on calling parse(NONE), the only change is to remove
the empty #else, which was my original patch.

"if no compression specification has been specified" is redundant with
"by default", and causes "not the others" to dangle.

If I were to rewrite the comment, it'd say:

+        * When gzip is available, custom and directory formats are compressed by
+        * default