Subject: Re: list of extended statistics on psql
To: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>,
 Tomas Vondra <tomas.vondra@2ndquadrant.com>
Cc: Michael Paquier <michael@paquier.xyz>,
 Pavel Stehule <pavel.stehule@gmail.com>,
 Alvaro Herrera <alvherre@2ndquadrant.com>,
 Julien Rouhaud <rjuju123@gmail.com>,
 PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
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From: Tomas Vondra <tomas.vondra@enterprisedb.com>
Message-ID: <b4172dc6-ac72-fa81-4a8a-3ca93cec7ccb@enterprisedb.com>
Date: Thu, 7 Jan 2021 01:56:18 +0100
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On 1/7/21 1:46 AM, Tatsuro Yamada wrote:
> Hi Tomas,
> 
>> Thanks, and Happy new year to you too.
>>
>> I almost pushed this, but I have one more question. listExtendedStats 
>> first checks the server version, and errors out for pre-10 servers. 
>> Shouldn't the logic building query check the server version too, to 
>> decide whether to check the MCV stats? Otherwise it won't work on 10 
>> and 11, which does not support the "mcv" stats.
>>> I don't recall what exactly is our policy regarding new psql with 
>>> older server versions, but it seems strange to check for 10.0 and 
>>> then fail anyway for "supported" versions.
> 
> Thanks for your comments.
> 
> 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.
> 

+1

BTW perhaps a quick look at the other \d commands would show if there 
are precedents. I didn't have time for that.

> I wonder the column names added by \dX+ is fine? For example,
> "Ndistinct_size" and "Dependencies_size". It looks like long names,
> but acceptable?
> 

Seems acceptable - I don't have a better idea.


regards

-- 
Tomas Vondra
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