David Geier <geidav(dot)pg(at)gmail(dot)com> writes:
> eqjoinsel() can be optimized by not reading MCV stats if at least one of
> the two join attributes is unique.
There won't *be* any MCV stats for a column that ANALYZE perceives to
be unique, so I'm not quite sure where the claimed savings comes from.
> With this change we saw some queries improve planning time by more than
> 2x, especially with larger values for default_statistics_target.
Please provide a concrete example.
regards, tom lane