On Thu, May 4, 2017 at 07:01:17PM -0300, Alvaro Herrera wrote:
> Thanks for doing this, looks great. A few notes:
>
> <listitem>
> <!--
> Author: Alvaro Herrera <[email protected]>
> 2017-03-24 [7b504eb28] Implement multivariate n-distinct coefficients
> Author: Simon Riggs <[email protected]>
> 2017-04-05 [2686ee1b7] Collect and use multi-column dependency stats
> -->
> <para>
> Add the ability to compute a correlation ratio and the number of
> distinct values on several columns (Tomas Vondra, David Rowley)
> </para>
>
> I think this should be worded in terms of "extended data statistics" or
> such. I think your proposed wording is a bit obscure. How about
> something like "Add extended statistics to improve query planning".
> Also, I'd add myself as co-author, with Tomas' permission.
I have adjusted the text to add your term, and added your name:
Add multi-column optimizer statistics to compute the correlation
ratio and number of distinct values (Tomas Vondra, David Rowley,
Álvaro Herrera)
I think we have to mention the exact statistics collected because we
know that they are of limited usefulness (per Tomas) and full
multi-column statistics are needed and hopefully coming in PG 11. If we
don't mention the details I am afraid people will be disappointed with PG
10 and will not be excited when they are more powerful in PG 11. Any
better wording?
I will work on the other items you posted shortly.
--
Bruce Momjian <[email protected]> http://momjian.us
EnterpriseDB http://enterprisedb.com
+ As you are, so once was I. As I am, so you will be. +
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