Обсуждение: [pgsql-advocacy] Correlated columns & firsts

Folks,

I had the impression that our new multicolumn stats feature was a first
in the industry.  However, a PDXPUG member said that SQL Server has
something like it for the last couple versions.

Anyone know if it's the same thing or not?

--
Josh Berkus
Containers & Databases Oh My!

On Wed, Jul 26, 2017 at 10:32 AM, Josh Berkus <josh@berkus.org> wrote:
> I had the impression that our new multicolumn stats feature was a first
> in the industry.  However, a PDXPUG member said that SQL Server has
> something like it for the last couple versions.

So does Oracle.

> Anyone know if it's the same thing or not?

I'm pretty sure that it is.

--
Peter Geoghegan

Josh Berkus wrote:
> Folks,
>
> I had the impression that our new multicolumn stats feature was a first
> in the industry.  However, a PDXPUG member said that SQL Server has
> something like it for the last couple versions.
>
> Anyone know if it's the same thing or not?

A quick search led me to
https://dba.stackexchange.com/questions/84747/statistics-are-multicolumn-histograms-possible
which contains a pointer to
https://blogs.msdn.microsoft.com/ianjo/2005/11/10/create-multi-column-statistics/

then you can see the MS docs at
https://docs.microsoft.com/en-us/sql/t-sql/statements/create-statistics-transact-sql
https://docs.microsoft.com/en-us/sql/relational-databases/statistics/statistics

From what I can tell, they only store the correlation between the
columns, so it's simpler than what we do.

--
Álvaro Herrera                https://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services