Date: Sun, 30 Aug 2020 18:48:18 +0200
From: Tomas Vondra <tomas.vondra@2ndquadrant.com>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
Cc: Tatsuro Yamada <tatsuro.yamada.tf@nttcom.co.jp>,
	Julien Rouhaud <rjuju123@gmail.com>,
	Pavel Stehule <pavel.stehule@gmail.com>,
	PostgreSQL Hackers <pgsql-hackers@lists.postgresql.org>
Subject: Re: list of extended statistics on psql
Message-ID: <20200830164818.b4rl4uk6wzfzrsys@development>
References: <20200829225436.atuttqilrcgppqio@development>
 <20200830163329.GA21915@alvherre.pgsql>
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On Sun, Aug 30, 2020 at 12:33:29PM -0400, Alvaro Herrera wrote:
>On 2020-Aug-30, Tomas Vondra wrote:
>
>> On Sat, Aug 29, 2020 at 06:43:47PM -0400, Alvaro Herrera wrote:
>> > On 2020-Aug-29, Tomas Vondra wrote:
>
>> > > Also, it might be useful to show the size of the statistics built, just
>> > > like we show for \d+ etc.
>> >
>> > \dX+  I  suppose?
>>
>> Right. I've only used \d+ as an example of an existing command showing
>> sizes of the objects.
>
>Yeah, I understood it that way too.
>
>How can you measure the size of the stat objects in a query?  Are you
>thinking in pg_column_size()?
>

Either that or simply length() on the bytea value.

>I wonder how to report that.  Knowing that psql \-commands are not meant
>for anything other than human consumption, maybe we can use a format()
>string that says "built: %d bytes" when \dX+ is used (for each stat type),
>and just "built" when \dX is used.  What do people think about this?
>

I'd use the same approach as \d+, i.e. a separate column with the size.
Maybe that'd mean too many columns, though.


regards

-- 
Tomas Vondra                  http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services