Re: Postgresql 11.3 doesn't use gist index on polygon column

=?UTF-8?B?0JLQsNC00LjQvCDQodCw0LzQvtGF0LjQvQ==?= <samokhinvadim(at)gmail(dot)com> writes:
> 6. But postgresql still doesn't want to use my index:
> postgres=# explain analyze select * from zonez where '(2,2)'::point <@ p;

It can't, because "polygon @> point" isn't one of the operators supported
by that opclass. You could use a polygon comparison:

=# \dAo gist poly_ops
List of operators of operator families
AM | Operator family | Operator | Strategy | Purpose
------+-----------------+----------------------+----------+----------
gist | poly_ops | <<(polygon,polygon) | 1 | search
gist | poly_ops | &<(polygon,polygon) | 2 | search
gist | poly_ops | &&(polygon,polygon) | 3 | search
gist | poly_ops | &>(polygon,polygon) | 4 | search
gist | poly_ops | >>(polygon,polygon) | 5 | search
gist | poly_ops | ~=(polygon,polygon) | 6 | search
gist | poly_ops | @>(polygon,polygon) | 7 | search
gist | poly_ops | <@(polygon,polygon) | 8 | search
gist | poly_ops | &<|(polygon,polygon) | 9 | search
gist | poly_ops | <<|(polygon,polygon) | 10 | search
gist | poly_ops | |>>(polygon,polygon) | 11 | search
gist | poly_ops | |&>(polygon,polygon) | 12 | search
gist | poly_ops | <->(polygon,point) | 15 | ordering
(13 rows)

regards, tom lane