From: Tom Lane <tgl@sss.pgh.pa.us>
To: Alvaro Herrera <alvherre@2ndquadrant.com>
cc: Tomas Vondra <tomas.vondra@2ndquadrant.com>,
        Simon Riggs <simon@2ndquadrant.com>,
        Andrew Dunstan <andrew.dunstan@2ndquadrant.com>,
        PostgreSQL-development <pgsql-hackers@postgresql.org>,
        Dean Rasheed <dean.a.rasheed@gmail.com>
Subject: Re: WITH clause in CREATE STATISTICS
In-reply-to: <20170512144322.35ntjwk45h2gyjm2@alvherre.pgsql>
References: <20170512144322.35ntjwk45h2gyjm2@alvherre.pgsql>
Comments: In-reply-to Alvaro Herrera <alvherre@2ndquadrant.com>
	message dated "Fri, 12 May 2017 11:43:22 -0300"
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Date: Fri, 12 May 2017 11:06:26 -0400
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Alvaro Herrera <alvherre@2ndquadrant.com> writes:
> Tom Lane wrote:
>> I'm prepared to create a fix for that, but it'd be easier to commit the
>> current patch first, to avoid merge conflicts.

> It seems we're mostly in agreement regarding the parts I was touching.
> Do you want to push your version of the patch?

It's still almost all your work, so I figured you should push it.

>> Hm.  OK, but then that example is pretty misleading, because it leads
>> the reader to suppose that the planner can tell the difference between
>> the selectivities of the two queries.  Maybe what's lacking is an
>> explanation of how you'd use this statistics type.

> I think we should remove the complex example from that page, and instead
> refer the reader to chapters 14 and 69.

Seems reasonable.  If we did add enough material there to be a standalone
description, it would be duplicative probably.  However, that does put
the onus on the other chapters to offer a complete definition, rather
than leaving details to the man page as we do in many other cases.

			regards, tom lane


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