From: Tom Lane <tgl@sss.pgh.pa.us>
To: Jeff Davis <pgsql@j-davis.com>
cc: Corey Huinker <corey.huinker@gmail.com>,
        Stephen Frost <sfrost@snowman.net>,
        Ashutosh Bapat <ashutosh.bapat.oss@gmail.com>,
        Matthias van de Meent <boekewurm+postgres@gmail.com>,
        Peter Smith <smithpb2250@gmail.com>,
        PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>,
        Tomas Vondra <tomas.vondra@enterprisedb.com>
Subject: Re: Statistics Import and Export
In-reply-to: <cea2d432215847a1d5cef1422ad1b21814f3f73b.camel@j-davis.com>
References: <Zei1xMGH8SJS9yoc@tamriel.snowman.net>
 <54f190b6c757da2a33cce811949e9dd9601fcba7.camel@j-davis.com>
 <1632327b74a734f8c434eb75e824160d2b06a697.camel@j-davis.com>
 <CADkLM=dOUfTtpmE70mx5SmdEs11hic61G-wPa45pB1iC3NRABg@mail.gmail.com>
 <16412b8b7ae443cb7470006beff3011927048860.camel@j-davis.com>
 <CADkLM=cq1n2wbxhV23pOeUKReBPZxZyELDsDJ3VAxkYBSVAe0g@mail.gmail.com>
 <CADkLM=d_WYoFq75eoNHso+9EFDi=Q2BtCmxQYMjrgLL4=v5dxw@mail.gmail.com>
 <1b1bd1ec39ab3de09a17bf7b241021067e5bd63c.camel@j-davis.com>
 <CADkLM=eJXPQD=pWwwm+4Y48haiMmznB8dCECNMrwr59niY8ESw@mail.gmail.com>
 <2bce855db8259c5672a09f863a307ca07b967b68.camel@j-davis.com>
 <CADkLM=dw=fkvPRmOw74UDYnLzXwkDyMSY1k2jsU5=xXBAj7Mpw@mail.gmail.com>
 <5e94c358caedf2a231dd71624c3578db7227a265.camel@j-davis.com>
 <CADkLM=dztWa9shWHyq=+rS9KvbZQ2v54tnOcYT+g8psf0B7w_A@mail.gmail.com>
 <CADkLM=fFwkd7VbO4SPCyX-2f-fyGraka5J+5fcp1QMrCefu68Q@mail.gmail.com>
 <CADkLM=cioQmOFh98qQmqVEkVPjLYszEhZtNtUbmmNAdHOSr3WQ@mail.gmail.com>
 <bf724b21-914a-4497-!
 ! 84e3-49944f9776f6@enterprisedb.com>
 <4afa70edab849ff16238d1100b6652404e9a4d9d.camel@j-davis.com>
 <CADkLM=e=_6dtacmrvd2NJWacOnQ3Zu5iaRZFgePL1=0L5-7P_w@mail.gmail.com>
 <3df03aa65aa6ea3a76582e1a792e422dc5c32ad3.camel@j-davis.com>
 <CAOuzzgpfm9hROr_g8LouvpOeqv4yxk3qXPXU9Sn2nnqzPpP5UA@mail.gmail.com>
 <718fa933c2c58d0ecc61995ab5c7ca1fe78d6369.camel@j-davis.com>
 <CAOuzzgqwxpq=3aNF_j5rvYmb71BHY4niZfpeJZFa-QLyLA1GFg@mail.gmail.com>
 <e16cd9caf4f5229a152d318d70b4d323a03e3539.camel@j-davis.com>
 <CADkLM=c8hAew1CdUBQNWr3r0dkZCu9DNhXV-X7ccLDNiQKhAnA@mail.gmail.com>
 <c3bc9b9eab819d9c6077b29588fca333ee2cbd80.camel@j-davis.com>
 <447200.1711819134@sss.pgh.pa.us>
 <cea2d432215847a1d5cef1422ad1b21814f3f73b.camel@j-davis.com>
Comments: In-reply-to Jeff Davis <pgsql@j-davis.com>
	message dated "Sat, 30 Mar 2024 10:29:43 -0700"
MIME-Version: 1.0
Content-Type: text/plain; charset="us-ascii"
Content-ID: <473883.1711820380.1@sss.pgh.pa.us>
Date: Sat, 30 Mar 2024 13:39:40 -0400
Message-ID: <473884.1711820380@sss.pgh.pa.us>
Archived-At: 
 <https://www.postgresql.org/message-id/473884.1711820380%40sss.pgh.pa.us>
Precedence: bulk

Jeff Davis <pgsql@j-davis.com> writes:
> On Sat, 2024-03-30 at 13:18 -0400, Tom Lane wrote:
>> Surely they are data, not schema.  It would make zero sense to
>> restore them if you aren't restoring the data they describe.

> The complexity is that pg_upgrade does create the data, but relies on a
> schema-only dump. So we'd need to at least account for that somehow,
> either with a separate stats-only dump, or make a special case in
> binary upgrade mode that dumps schema+stats (and resolves the CREATE
> INDEX issue).

Ah, good point.  But binary-upgrade mode is special in tons of ways
already.  I don't see a big problem with allowing it to dump stats
even though --schema-only would normally imply not doing that.

(You could also imagine an explicit positive --stats switch that would
override --schema-only, but I don't see that it's worth the trouble.)

>> Maybe we need to revisit CREATE INDEX's behavior rather
>> than assuming it's graven in stone?

> Would there be a significant cost to just not doing that? Or are you
> suggesting that we special-case the behavior, or turn it off during
> restore with a GUC?

I didn't have any specific proposal in mind, was just trying to think
outside the box.

			regards, tom lane