MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6 MASTER_POS_WAIT() Statement

SELECT MASTER_POS_WAIT('source_log_file', source_log_pos [, timeout][, channel])

This is actually a function, not a statement. It is used to ensure that the replica has read and executed events up to a given position in the source's binary log. See Section 12.21, “Miscellaneous Functions”, for a full description.