| From: | Andres Freund <andres(at)anarazel(dot)de> |
|---|---|
| To: | Tomas Vondra <tomas(dot)vondra(at)postgresql(dot)org> |
| Cc: | pgsql-committers(at)lists(dot)postgresql(dot)org |
| Subject: | Re: pgsql: Add support for multivariate MCV lists |
| Date: | 2019-03-27 19:04:06 |
| Message-ID: | 20190327190406.3gmupkthnbx7lvho@alap3.anarazel.de |
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| Lists: | pgsql-committers |
On 2019-03-27 19:02:01 +0000, Tomas Vondra wrote:
> Add support for multivariate MCV lists
>
> Introduce a third extended statistic type, supported by the CREATE
> STATISTICS command - MCV lists, a generalization of the statistic
> already built and used for individual columns.
>
> Compared to the already supported types (n-distinct coefficients and
> functional dependencies), MCV lists are more complex, include column
> values and allow estimation of much wider range of common clauses
> (equality and inequality conditions, IS NULL, IS NOT NULL etc.).
> Similarly to the other types, a new pseudo-type (pg_mcv_list) is used.
>
> Author: Tomas Vondra
> Reviewed-by: Dean Rasheed, David Rowley, Mark Dilger, Alvaro Herrera
> Discussion: https://postgr.es/m/dfdac334-9cf2-2597-fb27-f0fb3753f435@2ndquadrant.com
Congrats, this was long in the making!
- Andres
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