From: Tom Lane <tgl@sss.pgh.pa.us>
To: Julien Rouhaud <rjuju123@gmail.com>
cc: Andrew Dunstan <andrew@dunslane.net>,
        Alvaro Herrera <alvherre@alvh.no-ip.org>,
        David Rowley <dgrowleyml@gmail.com>, Peter Geoghegan <pg@bowt.ie>,
        Robert Haas <robertmhaas@gmail.com>,
        pgsql-hackers@lists.postgresql.org,
        Andrew <pgsqlhackers@andrewrepp.com>
Subject: Re: pg_dump versus hash partitioning
In-reply-to: <20230316090352.v2m2d473fcv5tli6@jrouhaud>
References: <1440373.1675299790@sss.pgh.pa.us> <a7ef6212-f9fe-6826-9640-5dac54327140@dunslane.net> <1533086.1675349554@sss.pgh.pa.us> <1912821.1676402493@sss.pgh.pa.us> <20230311030154.pg63uspio35h4a6t@jrouhaud> <1078804.1678504214@sss.pgh.pa.us> <20230311033232.g6jgkuzxdawepsbe@jrouhaud> <1602203.1678650412@sss.pgh.pa.us> <20230313083314.pivmgfu36fi4eu2n@jrouhaud> <2441413.1678750752@sss.pgh.pa.us> <20230316090352.v2m2d473fcv5tli6@jrouhaud>
Comments: In-reply-to Julien Rouhaud <rjuju123@gmail.com>
	message dated "Thu, 16 Mar 2023 17:03:52 +0800"
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Date: Thu, 16 Mar 2023 08:43:56 -0400
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Julien Rouhaud <rjuju123@gmail.com> writes:
> On Mon, Mar 13, 2023 at 07:39:12PM -0400, Tom Lane wrote:
>> Yeah, we need to do both.  Attached find an updated patch series:

> I didn't find a CF entry, is it intended?

Yeah, it's there:

https://commitfest.postgresql.org/42/4226/

> I'm not sure if you intend to keep the current 0002 - 0003 separation, b=
ut if
> yes the part about te->defn and possible fallback should be moved to 000=
3.  In
> 0002 we're only looking at the COPY statement.

I was intending to smash it all into one commit --- the separation is
just to ease review.

> I know you're only inheriting this comment, but isn't it well outdated a=
nd not
> accurate anymore?  I'm assuming that "archiving is not on" was an accept=
able
> way to mean "wal_level < archive" at some point, but it's now completely
> misleading.

Sure, want to propose wording?

> Hash partitioning was added with pg11, should we bypass pg10 too with a =
comment
> saying that we only care about hash, at least for the forseeable future?

Good point.  With v10 already out of support, it hardly matters in the
real world, but we might as well not expend cycles when we clearly
needn't.

> More generally, I also think that forcing --load-via-partition-root for
> known unsafe partitioning seems like the best compromise.  I'm not sure =
if we
> should have an option to turn it off though.

I think the odds of that yielding a usable dump are nil, so I don't
see why we should bother.

			regards, tom lane