Date: Fri, 15 Jan 2021 16:47:41 +0800
From: Julien Rouhaud <rjuju123@gmail.com>
To: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>
Cc: Tomas Vondra <tomas.vondra@enterprisedb.com>,
	Alvaro Herrera <alvherre@2ndquadrant.com>,
	Tomas Vondra <tomas.vondra@2ndquadrant.com>,
	Michael Paquier <michael@paquier.xyz>,
	Pavel Stehule <pavel.stehule@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: list of extended statistics on psql
Message-ID: <20210115084741.GA91293@nol>
References: <20210107144713.GA8872@alvherre.pgsql>
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 <1045d2cb-7ecd-e6bf-cb50-8eeea89cc4b0@nttcom.co.jp_1>
 <9e76ce7a-e7ab-5f08-9938-59fffc20d106@enterprisedb.com>
 <29e16ceb-8777-4297-19c8-245242dd7473@enterprisedb.com>
 <876efa7e-2067-a4f9-d7e8-f6025440c870@nttcom.co.jp_1>
 <0e84aa72-25f2-1849-753f-f827949132b3@enterprisedb.com>
 <85e7e1e7-c2f0-a4a0-61de-6e7ecaee44e3@nttcom.co.jp_1>
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On Wed, Jan 13, 2021 at 10:22:05AM +0900, Tatsuro Yamada wrote:
> Hi Tomas,
> 
> On 2021/01/13 7:48, Tatsuro Yamada wrote:
> > On 2021/01/12 20:08, Tomas Vondra wrote:
> > > On 1/12/21 2:57 AM, Tatsuro Yamada wrote:
> > > > On 2021/01/09 9:01, Tomas Vondra wrote:
> > > ...>
> > > > > While working on that, I realized that 'defined' might be a bit
> > > > > ambiguous, I initially thought it means 'NOT NULL' (which it does not).
> > > > > I propose to change it to 'requested' instead. Tatsuro, do you agree, or
> > > > > do you think 'defined' is better?
> > > > 
> > > > Regarding the status of extended stats, I think the followings:
> > > > 
> > > >   - "defined": it shows the extended stats defined only. We can't know
> > > >                whether it needs to analyze or not. I agree this name was
> > > >                 ambiguous. Therefore we should replace it with a more suitable
> > > >                name.
> > > >   - "requested": it shows the extended stats needs something. Of course,
> > > >                we know it needs to ANALYZE because we can create the patch.
> > > >                However, I feel there is a little ambiguity for DBA.
> > > >                To solve this, it would be better to write an explanation of
> > > >                the status in the document. For example,
> > > > 
> > > > ======
> > > > The column of the kind of extended stats (e. g. Ndistinct) shows some statuses.
> > > > "requested" means that it needs to gather data by ANALYZE. "built" means ANALYZE
> > > >   was finished, and the planner can use it. NULL means that it doesn't exists.
> > > > ======
> > > > 
> > > > What do you think? :-D
> > > > 
> > > 
> > > Yes, that seems reasonable to me. Will you provide an updated patch?
> > 
> > 
> > Sounds good. I'll send the updated patch today.
> 
> 
> 
> I updated the patch to add the explanation of the extended stats' statuses.
> Please feel free to modify the patch to improve it more clearly.
> 
> The attached files are:
>    0001: Add psql \dx and the fixed document
>    0002: Regression test for psql \dX
>    app-psql.html: Created by "make html" command (You can check the
>                   explanation of the statuses easily, probably)

Hello Yamada-san,

I reviewed the patch and don't have specific complaints, it all looks good!

I'm however thinking about the "requested" status.  I'm wondering if it could
lead to people think that an ANALYZE is scheduled and will happen soon.
Maybe "defined" or "declared" might be less misleading, or even "waiting for
analyze"?