Re: [GENERAL] Planner statistics usage for composite type - Mailing list pgsql-general

Tom,

* Tom Lane (tgl@sss.pgh.pa.us) wrote:
> Dmitry Lazurkin <dilaz03@gmail.com> writes:
> > I am trying to find workaround for cross-column statistics.
> > ...
> > Worn estimate. Planner doesn't use statistics. In code I see usage of
> > function scalargtsel which returns default selectivity because
> > ROW('tag1', 0.9)::tag_sim is not Const.
>
> Yeah, that's because eval_const_expressions doesn't know how to fold
> a constant RowExpr to a simple Const.  I have a patch laying about
> someplace to improve that, but I keep forgetting about it until
> we're in beta phase :-(.  In the meantime you could perhaps do the
> folding by hand:

Put it into the CF..?

Thanks!

Stephen