Re: pg_basebackup and error messages dependent on the order of the arguments

>> As this example shows, we really ought to validate the compression
>> argument on sight in order to get sensible error messages.  The
>> trouble is that for server-side compression the code wants to just
>> pass the string through to the server and not form its own opinion
>> as to whether it's a known algorithm.

>> Perhaps it would help if we simply rejected strings beginning
>> with a dash?  I haven't tested, but roughly along the lines of

>Taking a closer look, many of the other switches-requiring-an-argument
>also just absorb "optarg" without checking its value till much later,
>so I'm not sure how far we could move the needle by special-casing
>--compress.

My point was not so much about --compress but rather giving a good error message.

Looking at this:

$ pg_basebackup --checkpoint=fast --format=t --compress --pgdata=/var/tmp/dummy
pg_basebackup: error: must specify output directory or backup target

... the error message is misleading and will confuse users more than it helps.

Regards

Daniel