Re: spgist index not getting used

Paul Ramsey <pramsey(at)cleverelephant(dot)ca> writes:
> My C implementation is herehttps://github.com/pramsey/postgis/blob/spgist/postgis/gserialized_spgist_2d.c
> My SQL binding calls are herehttps://github.com/pramsey/postgis/blob/spgist/postgis/gserialized_spgist_2d.sql

> Thanks to help from Andres Freund, I can now build an index based on my extension. However, when I run a query using the operator(s) I have defined, the query never uses my index, it always sequence scans.

> explain analyze select * from somepoints where '(5898.82450178266,7990.24286679924)'::point = pt;

(I assume that's a typo and you meant "... &=& pt")

As stated, this WHERE clause cannot be used with the index: indexable
clauses in PG are always of the form "indexed_column operator something",
and you've written it the other way round. I gather that you think the
operator is commutative; but since you didn't declare that, the planner
doesn't know it can flip the clause around. Try adding "commutator = &=&"
to the declaration of the "point &=& point" operator.

regards, tom lane