Subject: Re: list of extended statistics on psql
To: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>,
 Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>,
 Michael Paquier <michael@paquier.xyz>,
 Pavel Stehule <pavel.stehule@gmail.com>, Julien Rouhaud
 <rjuju123@gmail.com>, PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
References: <20210107144713.GA8872@alvherre.pgsql>
 <61cba5af-5a58-6bda-610c-420077b780c3@enterprisedb.com>
 <1045d2cb-7ecd-e6bf-cb50-8eeea89cc4b0@nttcom.co.jp_1>
From: Tomas Vondra <tomas.vondra@enterprisedb.com>
Message-ID: <9e76ce7a-e7ab-5f08-9938-59fffc20d106@enterprisedb.com>
Date: Fri, 8 Jan 2021 01:14:39 +0100
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On 1/8/21 12:52 AM, Tatsuro Yamada wrote:
> Hi,
> 
> On 2021/01/08 0:56, Tomas Vondra wrote:
>> On 1/7/21 3:47 PM, Alvaro Herrera wrote:
>>> On 2021-Jan-07, Tomas Vondra wrote:
>>>
>>>> On 1/7/21 1:46 AM, Tatsuro Yamada wrote:
>>>
>>>>> I overlooked the check for MCV in the logic building query
>>>>> because I created the patch as a new feature on PG14.
>>>>> I'm not sure whether we should do back patch or not. However, I'll
>>>>> add the check on the next patch because it is useful if you decide to
>>>>> do the back patch on PG10, 11, 12, and 13.
>>>>
>>>> BTW perhaps a quick look at the other \d commands would show if 
>>>> there are
>>>> precedents. I didn't have time for that.
>>>
>>> Yes, we do promise that new psql works with older servers.
>>>
>>
>> Yeah, makes sense. That means we need add the check for 12 / MCV.
> 
> 
> Ah, I got it.
> I fixed the patch to work with older servers to add the checking 
> versions. And I tested \dX command on older servers (PG10 - 13).
> These results look fine.
> 
> 0001:
>       Added the check code to handle pre-PG12. It has not MCV and
>        pg_statistic_ext_data.
> 0002:
>       This patch is the same as the previous patch (not changed).
> 
> Please find the attached files.
> 

OK, thanks. I'll take a look and probably push tomorrow. FWIW I plan to 
squash the patches into a single commit.

regards

-- 
Tomas Vondra
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