GIN Expression Indexes

[Taylor Sarrafian]

Hi friends!

We tried to index an array function like this:

  CREATE INDEX my_arr_index ON my_table USING GIN ( my_arr_func( my_col ) )

But the planner can’t seem to figure out how to use the index with any query! 
It doesn’t work with any array operators.

  SELECT * FROM my_table WHERE ARRAY[ 123 ]::INT[] && my_arr_func( my_col )

Even weirder, an empty array correctly uses the index:

  SELECT * FROM my_table WHERE ARRAY[]::INT[] && my_arr_func( my_col )

Is there any way to coerce Postgres into using this index? Thanks!

ts