Miscellaneous Functions operation is called to update the status of the replica. Depending on the setting for the system variables, the function might therefore return some time after the specified position was reached. If binary log transaction compression is in use and the transaction payload at the specified position is compressed (as a  Transaction_payload_event ), the function waits until the whole transaction has been read and applied, and the positions have updated. If a  timeout  value is specified,  MASTER_POS_WAIT()  stops waiting when  timeout  seconds have elapsed.  timeout  must be greater than 0; a zero or negative  timeout  means no timeout. The optional  channel  value enables you to name which replication channel the function applies to. See Section 17.2.2, “Replication Channels”  for more information. This function is unsafe for statement-based replication. A warning is logged if you use this function when binlog_format  is set to  STATEMENT . Returns the given value. When used to produce a result set column,  NAME_CONST()  causes the column to have the given name. The arguments should be constants. • NAME_CONST( name , value ) mysql>  SELECT NAME_CONST(’myname’, 14); +--------+ | myname | +--------+ | 14 | +--------+ This function is for internal use only. The server uses it when writing statements from stored programs that contain references to local program variables, as described in Section 25.7, “Stored Program Binary Logging” . You might see this function in the output from  mysqlbinlog . For your applications, you can obtain exactly the same result as in the example just shown by using simple aliasing, like this: See Section 13.2.10, “SELECT Statement” , for more information about column aliases. mysql>  SELECT 14 AS myname; +--------+ | myname | +--------+ | 14 | +--------+ 1 row in set (0.00 sec) • SLEEP( duration ) Sleeps (pauses) for the number of seconds given by the  duration  argument, then returns 0. The duration may have a fractional part. If the argument is  NULL  or negative,  SLEEP()  produces a warning, or an error in strict SQL mode. When sleep returns normally (without interruption), it returns 0: mysql>  SELECT SLEEP(1000); +-------------+ | SLEEP(1000) | +-------------+ | 0 | 2449