Re: pg_dump --with-* options - Mailing list pgsql-hackers

On 2025/06/25 5:07, Robert Haas wrote:
> On Tue, Jun 24, 2025 at 12:48 PM Nathan Bossart
> <nathandbossart@gmail.com> wrote:
>> On Mon, Jun 23, 2025 at 01:38:10PM -0400, Robert Haas wrote:
>>> I had thought we had a consensus that pg_upgrade should preserve stats
>>> but regularly pg_dump shouldn't include them; perhaps I misunderstood
>>> or that changed.
>>
>> I think it's a bit of both.  I skimmed through the past discussions and
>> found that not only was there a rough consensus in 2024 that stats _should_
>> be on by default [0], but also that an updated vote tally didn't show much
>> of a consensus at all [1].  Like you, I thought we had pretty much closed
>> that door, but the aforementioned analysis along with further discussion
>> has me convinced that we might want to reconsider [2].
> 
> Well, I don't know: I still think that's the right answer, so I don't
> really want to reconsider, but I understand that I'm not in charge
> here.

For the record, my vote is: default "off" for pg_dump and pg_dumpall,
and "on" for pg_restore.

For pg_dump and pg_dumpall, I agree with Jeff's idea in [1],
but if the statistics is skipped by default, I don't think
we need a --no-statistics option. So, here's how I think
the options should work:

     * Keep: --schema-only, --data-only, --statistics-only, --no-schema, --no-data, -and -statistics
     * Remove: --no-statistics, --with-schema, and --with-data
     * Combinations:
         Schema + Data + Stats     : --statistics
         Schema + Data             : (default)
         Schema + Stats            : --no-data --statistics
         Data + Stats              : --no-schema --statistics
         Schema only               : --schema-only   (or --no-data)
         Data only                 : --data-only     (or --no-schema)
         Stats only                : --statistics-only (or --no-schema --no-data --statistics)

As I mentioned in [2], if we treat --statistics in the similar way to
--sequence-data, i.e., allow --statistics to be used with --schema-only
or --data-only, we could simplify further:

     * Keep: --schema-only, --data-only, --statistics-only, and --statistics
     * Remove: --no-schema, --no-data, --no-statistics, --with-schema, and --with-data
     * Combinations:
         Schema + Data + Stats     : --statistics
         Schema + Data             : (default)
         Schema + Stats            : --schema-only --statistics
         Data + Stats              : --data-only --statistics
         Schema only               : --schema-only
         Data only                 : --data-only
         Stats only                : --statistics-only

Some may find this confusing due to mixing --statistics with --schema-only
or --data-only, so I understand if there's hesitation.

For pg_restore, I believe there's agreement to restore statistics
by default if they exist in the archive. So:

     * Keep: --schema-only, --data-only, --statistics-only, --no-schema, --no-data, and --no-statistics
     * Remove: --with-schema, --with-data, and --statistics
     * Combinations:
         Schema + Data + Stats     : (default)
         Schema + Data             : --no-statistics
         Schema + Stats            : --no-data
         Data + Stats              : --no-schema
         Schema only               : --schema-only   (or --no-data --no-statistics)
         Data only                 : --data-only     (or --no-schema --no-statistics)
         Stats only                : --statistics-only (or --no-schema --no-data)

Thought?

Regards,

[1] https://postgr.es/m/031558c60e84362898922caa6a90587e7fdf2a57.camel@j-davis.com
[2] https://postgr.es/m/94f89b0a-5d83-4a67-9092-50ba3913441c@oss.nttdata.com

-- 
Fujii Masao
NTT DATA Japan Corporation