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

=?UTF-8?B?0JLQsNC00LjQvCDQodCw0LzQvtGF0LjQvQ==?= <samokhinvadim@gmail.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