================================================================================
basic
================================================================================
create index ON foo.bar(col);
--------------------------------------------------------------------------------

(source_file
  (create_index_statement
    (identifier)
    (index_col
      (identifier))))

================================================================================
with columns
================================================================================
create index on foo.bar (
    col ASC NULLS FIRST,
    col DESC NULLS LAST,
    col NULLS FIRST,
    (upper(col)) DESC);
--------------------------------------------------------------------------------

(source_file
  (create_index_statement
    (identifier)
    (index_col
      (identifier)
      (index_col_dir)
      (index_col_nulls))
    (index_col
      (identifier)
      (index_col_dir)
      (index_col_nulls))
    (index_col
      (identifier)
      (index_col_nulls))
    (index_col
      (function_call
        (identifier)
        (identifier))
      (index_col_dir))))

================================================================================
full syntax
================================================================================
create unique index concurrently if not exists idx_name on foo.bar using gist (col, (upper(bar)));
--------------------------------------------------------------------------------

(source_file
  (create_index_statement
    (if_not_exists)
    (identifier)
    (identifier)
    (index_using
      (identifier))
    (index_col
      (identifier))
    (index_col
      (function_call
        (identifier)
        (identifier)))))

================================================================================
include
================================================================================
create index ON foo.bar(col) include (col1, col2);
--------------------------------------------------------------------------------

(source_file
  (create_index_statement
    (identifier)
    (index_col
      (identifier))
    (index_includes
      (identifier)
      (identifier))))

================================================================================
partial
================================================================================
create index ON foo.bar(col) where col > 25;
--------------------------------------------------------------------------------

(source_file
  (create_index_statement
    (identifier)
    (index_col
      (identifier))
    (where_filter
      (op_expression
        (identifier)
        (comparison_op)
        (number)))))