Date: Sun, 28 Apr 2024 09:54:16 -0500
From: Justin Pryzby <pryzby@telsasoft.com>
To: Alexander Korotkov <aekorotkov@gmail.com>
Cc: Dmitry Koval <d.koval@postgrespro.ru>,
	Alexander Lakhin <exclusion@gmail.com>,
	Robert Haas <robertmhaas@gmail.com>,
	Tomas Vondra <tomas.vondra@enterprisedb.com>,
	Alvaro Herrera <alvherre@alvh.no-ip.org>,
	pgsql-hackers@lists.postgresql.org
Subject: Re: Add SPLIT PARTITION/MERGE PARTITIONS commands
Message-ID: <Zi5jGIXBptRcH0UV@pryzbyj2023>
References: <CAPpHfdv-uR663BO6G2kRuLEQjob+UBHuD3iyXF+qGHXQFRN0-Q@mail.gmail.com>
 <56e0000c-6b39-44ce-90b4-d3c3062e408c@postgrespro.ru>
 <CAPpHfdvShLh5txtQdh6=ZMCnzGZHv8W+RHAe8pY94rfzghWTAg@mail.gmail.com>
 <5dee3937-8e9f-cca4-11fb-737709a92b37@gmail.com>
 <f8b5cbf5-965e-4e5b-b506-33bbf41b0d50@postgrespro.ru>
 <CAPpHfdtLk5M4FV6C33DnBusWpsbwwmrQ83mpu7N8PZMupbftyw@mail.gmail.com>
 <CAPpHfdtB9L1C7HLE30WDQfQQgUZo5P+5=9kLr5vQSpDZ-2AV_A@mail.gmail.com>
 <ZilrByTp-pbz6Mvf@pryzbyj2023>
 <CAPpHfds8syFKMRkOFVTwiqoQ1oqPs_bboPk+Sgt7cDKOZxnhhg@mail.gmail.com>
 <Zi5Msg74C61DjJKW@pryzbyj2023>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <Zi5Msg74C61DjJKW@pryzbyj2023>
Archived-At: <https://www.postgresql.org/message-id/Zi5jGIXBptRcH0UV%40pryzbyj2023>
Precedence: bulk

On Sun, Apr 28, 2024 at 08:18:42AM -0500, Justin Pryzby wrote:
> > I will explore this.  Do we copy extended stats when we do CREATE
> > TABLE ... PARTITION OF?  I think we need to do the same here.
> 
> Right, they're not copied because an extended stats objs on the parent
> does something different than putting stats objects on each child.
> I've convinced myself that it's wrong to copy the parent's stats obj.
> If someone wants stats objects on each child, they'll have to handle
> them specially after MERGE/SPLIT, just as they would for per-child
> defaults/constraints/etc.

I dug up this thread, in which the idea of copying extended stats from
parent to child was considered some 6 years ago, but never implemented;
for consistency, MERGE/SPLIT shouldn't copy extended stats, either.

https://www.postgresql.org/message-id/20180305195750.aecbpihhcvuskzba%40alvherre.pgsql

-- 
Justin