Thread: Simplifications for error messages related to compression
Hi all, While looking at a different patch, I have noticed that the error messages produced by pg_basebackup and pg_dump are a bit inconsistent with the other others. Why not switching all of them as of the attached? This reduces the overall translation effort, using more: "this build does not support compression with %s" Thoughts or objections? -- Michael
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On Mon, Dec 19, 2022 at 02:42:13PM +0900, Michael Paquier wrote: > Thoughts or objections? Hearing nothing, done.. -- Michael
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On Wed, Dec 21, 2022 at 10:43:19AM +0900, Michael Paquier wrote:
> On Mon, Dec 19, 2022 at 02:42:13PM +0900, Michael Paquier wrote:
> > Thoughts or objections?
>
> Hearing nothing, done..
- pg_fatal("not built with zlib support");
+ pg_fatal("this build does not support compression with %s", "gzip");
I tried to say in the other thread that gzip != zlib.
This message may be better for translation, but (for WriteDataToArchive
et al) the message is now less accurate, and I suspect will cause some
confusion.
5e73a6048 introduced a similar user-facing issue: pg_dump -Fc -Z gzip
does not output a gzip.
$ ./tmp_install/usr/local/pgsql/bin/pg_dump -h /tmp -Fc -Z gzip regression |xxd |head
00000000: 5047 444d 5001 0e00 0408 0101 0100 0000 PGDMP...........
I'm okay with it if you think this is no problem - maybe it's enough to
document that the output is zlib and not gzip.
Otherwise, one idea was to reject "gzip" with -Fc. It could accept
integers only.
BTW I think it's helpful to include the existing participants when
forking a thread.
--
Justin
On Tue, Dec 20, 2022 at 08:29:32PM -0600, Justin Pryzby wrote:
> - pg_fatal("not built with zlib support");
> + pg_fatal("this build does not support compression with %s", "gzip");
>
> I tried to say in the other thread that gzip != zlib.
>
> This message may be better for translation, but (for WriteDataToArchive
> et al) the message is now less accurate, and I suspect will cause some
> confusion.
Compression specifications use this term, so, like bbstreamer_gzip.c,
that does not sound like a big difference to me as everything depends
on HAVE_LIBZ, still we use gzip for all the user-facing terms.
> 5e73a6048 introduced a similar user-facing issue: pg_dump -Fc -Z gzip
> does not output a gzip.
We've never mentioned any compression method in the past docs, just
that things can be compressed.
> $ ./tmp_install/usr/local/pgsql/bin/pg_dump -h /tmp -Fc -Z gzip regression |xxd |head
> 00000000: 5047 444d 5001 0e00 0408 0101 0100 0000 PGDMP...........
>
> I'm okay with it if you think this is no problem - maybe it's enough to
> document that the output is zlib and not gzip.
Perhaps.
> Otherwise, one idea was to reject "gzip" with -Fc. It could accept
> integers only.
I am not sure what we would gain by doing that, except complications
with the code surrounding the handling of compression specifications,
which is a backward-compatible thing as it can handle integer-only
inputs.
> BTW I think it's helpful to include the existing participants when
> forking a thread.
Err, okay.. Sorry about that.
--
Michael
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On Wed, Dec 21, 2022 at 01:52:21PM +0900, Michael Paquier wrote:
> On Tue, Dec 20, 2022 at 08:29:32PM -0600, Justin Pryzby wrote:
> > - pg_fatal("not built with zlib support");
> > + pg_fatal("this build does not support compression with %s", "gzip");
> >
> > I tried to say in the other thread that gzip != zlib.
> >
> > This message may be better for translation, but (for WriteDataToArchive
> > et al) the message is now less accurate, and I suspect will cause some
> > confusion.
>
> Compression specifications use this term, so, like bbstreamer_gzip.c,
Yes, and its current users (basebackup) output a gzip file, right ?
pg_dump -Fc doesn't output a gzip file, but now it's using user-facing
compression specifications referring to it as "gzip".
> that does not sound like a big difference to me as everything depends
> on HAVE_LIBZ, still we use gzip for all the user-facing terms.
postgres is using -lz to write both gzip files and non-gzip libz files;
its associated compiletime constant has nothing to do with which header
format is being output.
* This file includes two APIs for dealing with compressed data. The first
* provides more flexibility, using callbacks to read/write data from the
* underlying stream. The second API is a wrapper around fopen/gzopen and
* friends, providing an interface similar to those, but abstracts away
* the possible compression. Both APIs use libz for the compression, but
* the second API uses gzip headers, so the resulting files can be easily
* manipulated with the gzip utility.
> > 5e73a6048 introduced a similar user-facing issue: pg_dump -Fc -Z gzip
> > does not output a gzip.
>
> We've never mentioned any compression method in the past docs, just
> that things can be compressed.
What do you mean ?
The commit added:
+ The compression method can be set to <literal>gzip</literal> or ...
And the docs still say:
- For plain text output, setting a nonzero compression level causes
- the entire output file to be compressed, as though it had been
- fed through <application>gzip</application>; but the default is not to compress.
If you tell someone they can write -Z gzip, they'll be justified in
expecting to see "gzip" as output.
--
Justin
On Tue, Dec 20, 2022 at 11:12:22PM -0600, Justin Pryzby wrote: > Yes, and its current users (basebackup) output a gzip file, right ? > > pg_dump -Fc doesn't output a gzip file, but now it's using user-facing > compression specifications referring to it as "gzip". Not all of them are compressed either, like the base TOC file. > If you tell someone they can write -Z gzip, they'll be justified in > expecting to see "gzip" as output. That's the point where my interpretation is different than yours, where I don't really see as an issue that we do not generate a gzip file all the time in the output. Honestly, I am not sure that there is anything to win here by not using the same option interface for all the binaries or have tweaks to make pg_dump cope with that (like using zlib as an extra alias). The custom, directory and tar formats of pg_dumps have their own idea of the files to compress or not (like the base TOC file is never compressed so as one can do a pg_restore -l). -- Michael