Thread: PG 14 pg_basebackup accepts --compress=server-zst option

PG 14 pg_basebackup accepts --compress=server-zst option

From
Ron Johnson
Date:

https://www.postgresql.org/docs/14/app-pgbasebackup.html doesn't mention "--compress=[{client|server}-]method".  That first appears in the v15 docs.

And yet pg_basebackup doesn't complain about an invalid option.  (Technically, this is a bug; I first noticed it a week after copying a script from a PG 15 server to five PG 14 servers, and running it quite a few times without fail.)

$ pg_basebackup \
>             --pgdata=$PGDATA \
>             --dbname=service=basebackup \
>             --verbose --progress \
>             --checkpoint=fast \
>             --write-recovery-conf \
>             --wal-method=stream \
>             --create-slot --slot=pgstandby1 \
>             --compress=server-zst ; echo $?
pg_basebackup: initiating base backup, waiting for checkpoint to complete
pg_basebackup: checkpoint completed
pg_basebackup: write-ahead log start point: 256/BC000028 on timeline 1
pg_basebackup: starting background WAL receiver
pg_basebackup: created replication slot "pgstandby1"
42567083/42567083 kB (100%), 1/1 tablespace                                pg_basebackup: write-ahead log end point: 256/BC000138
pg_basebackup: waiting for background process to finish streaming ...
pg_basebackup: syncing data to disk ...
pg_basebackup: renaming backup_manifest.tmp to backup_manifest
pg_basebackup: base backup completed
0


Re: PG 14 pg_basebackup accepts --compress=server-zst option

From
Kashif Zeeshan
Date:
Hi

On Fri, Jun 7, 2024 at 6:54 AM Ron Johnson <ronljohnsonjr@gmail.com> wrote:

https://www.postgresql.org/docs/14/app-pgbasebackup.html doesn't mention "--compress=[{client|server}-]method".  That first appears in the v15 docs.

And yet pg_basebackup doesn't complain about an invalid option.  (Technically, this is a bug; I first noticed it a week after copying a script from a PG 15 server to five PG 14 servers, and running it quite a few times without fail.)
If the support is removed then it should be mentioned in the official documentation.

Regards
Kashif Zeeshan
Bitnine Global 

$ pg_basebackup \
>             --pgdata=$PGDATA \
>             --dbname=service=basebackup \
>             --verbose --progress \
>             --checkpoint=fast \
>             --write-recovery-conf \
>             --wal-method=stream \
>             --create-slot --slot=pgstandby1 \
>             --compress=server-zst ; echo $?
pg_basebackup: initiating base backup, waiting for checkpoint to complete
pg_basebackup: checkpoint completed
pg_basebackup: write-ahead log start point: 256/BC000028 on timeline 1
pg_basebackup: starting background WAL receiver
pg_basebackup: created replication slot "pgstandby1"
42567083/42567083 kB (100%), 1/1 tablespace                                pg_basebackup: write-ahead log end point: 256/BC000138
pg_basebackup: waiting for background process to finish streaming ...
pg_basebackup: syncing data to disk ...
pg_basebackup: renaming backup_manifest.tmp to backup_manifest
pg_basebackup: base backup completed
0


Re: PG 14 pg_basebackup accepts --compress=server-zst option

From
"David G. Johnston"
Date:
On Thursday, June 6, 2024, Kashif Zeeshan <kashi.zeeshan@gmail.com> wrote:
Hi

On Fri, Jun 7, 2024 at 6:54 AM Ron Johnson <ronljohnsonjr@gmail.com> wrote:

https://www.postgresql.org/docs/14/app-pgbasebackup.html doesn't mention "--compress=[{client|server}-]method".  That first appears in the v15 docs.

And yet pg_basebackup doesn't complain about an invalid option.  (Technically, this is a bug; I first noticed it a week after copying a script from a PG 15 server to five PG 14 servers, and running it quite a few times without fail.)

Seems a bit suspect, but as your script doesn’t mention tar the option itself is apparently ignored, I guess silently.  Assuming this isn’t an actual regression in behavior in a patch-released older version I don’t see us adding an error message at this point.
 
If the support is removed then it should be mentioned in the official documentation.

Support wasn’t removed.  Re-read the email and check the version/times being mentioned again.

David J.

Re: PG 14 pg_basebackup accepts --compress=server-zst option

From
Ron Johnson
Date:
On Fri, Jun 7, 2024 at 12:32 AM David G. Johnston <david.g.johnston@gmail.com> wrote:
On Thursday, June 6, 2024, Kashif Zeeshan <kashi.zeeshan@gmail.com> wrote:
Hi

On Fri, Jun 7, 2024 at 6:54 AM Ron Johnson <ronljohnsonjr@gmail.com> wrote:

https://www.postgresql.org/docs/14/app-pgbasebackup.html doesn't mention "--compress=[{client|server}-]method".  That first appears in the v15 docs.

And yet pg_basebackup doesn't complain about an invalid option.  (Technically, this is a bug; I first noticed it a week after copying a script from a PG 15 server to five PG 14 servers, and running it quite a few times without fail.)

Seems a bit suspect, but as your script doesn’t mention tar the option itself is apparently ignored, I guess silently. 

Does this mean that "--compress=server-zst" is only relevant with --format=tar?
 
Assuming this isn’t an actual regression in behavior in a patch-released older version

My apologies for not mentioning the version: 14.12-1PGDG-rhel8.
 
I don’t see us adding an error message at this point.

Me neither.  It just seemed odd.

Re: PG 14 pg_basebackup accepts --compress=server-zst option

From
Tom Lane
Date:
Ron Johnson <ronljohnsonjr@gmail.com> writes:
> On Fri, Jun 7, 2024 at 12:32 AM David G. Johnston <
> david.g.johnston@gmail.com> wrote:
>> I don’t see us adding an error message at this point.

> Me neither.  It just seemed odd.

v14 thinks the argument of --compress must be an integer, and doesn't
really bother with any syntax error checks:

            case 'Z':
                compresslevel = atoi(optarg);
                if (compresslevel < 0 || compresslevel > 9)
                {
                    pg_log_error("invalid compression level \"%s\"", optarg);
                    exit(1);
                }
                break;

In your example, atoi() will return zero and it will sail along with
no compression.  Releases 15 and up have more complex ideas of what
--compress can specify, and seem to syntax-check it much more
thoroughly.

This is a pretty common coding pattern, so I can't get excited
about changing it, especially not in long-stable branches.

            regards, tom lane