add_index_options

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 894
        def add_index_options(table_name, column_name, **options) # :nodoc:
          if (where = options[:where]) && table_exists?(table_name) && column_exists?(table_name, where)
            options[:where] = quote_column_name(where)
          end
          super
        end