On 02/21/2017 12:13 AM, Bruce Momjian wrote:
> At the risk of asking a stupid question, we already have optimizer
> statistics on expression indexes. In what sense are we using this for
> multi-variate statistics, and in what sense can't we.
>
We're not using that at all, because those are really orthogonal
features. Even with expression indexes, the statistics are per
attribute, and the attributes are treated as independent.
There was a proposal to also allow creating statistics on expressions
(without having to create an index), but that's not supported yet.
regards
--
Tomas Vondra http://www.2ndQuadrant.com
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services
