content_image/804963.jpg content_image/804960.jpg content_image/804961.jpg
key: PRIMARY key_len: 4 ref: employees.de.emp_no rows: 1 Extra: Child of ’de’ in pushed join@1 *************************** 4. row *************************** id: 1 select_type: SIMPLE table: t type: ref possible_keys: PRIMARY,emp_no key: emp_no key_len: 4 ref: employees.de.emp_no rows: 19 Extra: Child of ’e’ in pushed join@1 4 rows in set (0.00 sec) 

<img src='content_image/804963.jpg'>

## Note 

If inner joined child tables are joined by ref , and  the result is ordered or grouped by a sorted index, this index cannot provide sorted rows, which forces writing to a sorted tempfile. 

Two additional sources of information about pushed join performance are available: 

1. The status variables Ndb_pushed_queries_defined , Ndb_pushed_queries_dropped , Ndb_pushed_queries_executed , and Ndb_pushed_reads . 

2. The counters in the ndbinfo.counters  table that belong to the DBSPJ  kernel block. 

• ndb_log_apply_status 

<img src='content_image/804960.jpg'>

A read-only variable which shows whether the server was started with the --ndb-log-apply-status option. 

• ndb_log_bin 

<img src='content_image/804961.jpg'>

