instance method change_column

# File activerecord/lib/active_record/connection_adapters/postgresql/schema_statements.rb, line 438
        def change_column(table_name, column_name, type, options = {})
          clear_cache!
          quoted_table_name = quote_table_name(table_name)
          sql_type = type_to_sql(type, options[:limit], options[:precision], options[:scale])
          sql_type << "[]" if options[:array]
          sql = "ALTER TABLE #{quoted_table_name} ALTER COLUMN #{quote_column_name(column_name)} TYPE #{sql_type}"
          sql << " USING #{options[:using]}" if options[:using]
          if options[:cast_as]
            sql << " USING CAST(#{quote_column_name(column_name)} AS #{type_to_sql(options[:cast_as], options[:limit], options[:precision], options[:scale])})"
          end
          execute sql

          change_column_default(table_name, column_name, options[:default]) if options_include_default?(options)
          change_column_null(table_name, column_name, options[:null], options[:default]) if options.key?(:null)
        end