why the temporary table has no content

i use percona server ,when i check information_schema.global_temporary_table and temporary_table,i find nothing,but i can observe a lot of temp table from my temp dir

ls /data/mysql_tmp_no_del/

#sql_196c_1.MYD #sql_196c_1.MYI #sql_196c_5.MYD #sql_196c_5.MYI #sql_196c_6.MYD #sql_196c_6.MYI #sql_196c_7.MYD #sql_196c_7.MYI #sql_196c_8.MYD #sql_196c_8.MYI

mysql> show temporary tables;
Empty set (0.00 sec)

mysql> show temporary tables;
Empty set (0.00 sec)

mysql> show global temporary tables;
Empty set (0.00 sec)

mysql> select version();
±--------------+
| version() |
±--------------+
| 5.5.20-55-log |
±--------------+
1 row in set (0.00 sec)

mysql> use information_schema;
Reading table information for completion of table and column names
You can turn off this feature to get a quicker startup with -A

Database changed
mysql> select * from GLOBAL_TEMPORARY_TABLES\G
Empty set (0.00 sec)

mysql> select * from TEMPORARY_TABLES\G
Empty set (0.00 sec)

This table apparently shows only tables created with CREATE TEMPORARY TABLE, not those created implicitly to process complex queries. I have asked for a documentation clarification, here: https://bugs.launchpad.net/percona-server/+bug/949030 Please vote for or comment on this bug report if it is important to you.