Re: pg_dump --with-* options

On 2025/06/12 22:47, Peter Eisentraut wrote:
> On 06.06.25 17:39, Nathan Bossart wrote:
>> On Fri, Jun 06, 2025 at 09:14:32AM +0200, Peter Eisentraut wrote:
>>> We have
>>>
>>>    -a, --data-only      dump only the data, not the schema or statistics
>>>    --no-data            do not dump data
>>>    --with-data          dump the data  # this one is new
>>>
>>> (and there is also --section=data), and then three analogous options for
>>> "schema" and "statistics".
>>>
>>> What is the purpose of the --with-data option?  Dumping the data is the
>>> default.  Is this to override an earlier --no-data option?
>>
>> I believe the idea is that these will allow folks to be explicit about what
>> they want instead of needing to understand the defaults for every
>> component.
> 
> I get that idea, but we really need some more documentation for this, I think.  So far I could only guess how this is supposed to be used, and I also happened to guess wrong.
> 
> My initial guess was that --with-data can override --no-data.  That would have been pretty standard "last option wins" behavior.  But pg_dump rejects that.  Personally, I think that is kind of wrong.
> 
> But you can use --with-data to override, say, --schema-only.  That also seems kind of wrong to me, but anyway.

While testing pg_dump --with-* in relation to bug #18952 [1],
I also ran into this behavior. It was surprising,
as I expected pg_dump to reject that combination of options.
The current behavior seems confusing.

Regards,

[1] https://postgr.es/m/18952-be40a620f8b1e755@postgresql.org

-- 
Fujii Masao
NTT DATA Japan Corporation