Syntax

MASTER_POS_WAIT(log_name,log_pos[,timeout,["connection_name"]])

Description

This function is useful in replication for controlling master/slave synchronization. It blocks until the slave has read and applied all updates up to the specified position (log_name,log_pos) in the master log. The return value is the number of log events the slave had to wait for to advance to the specified position. The function returns NULL if the slave SQL thread is not started, the slave's master information is not initialized, the arguments are incorrect, or an error occurs. It returns -1 if the timeout has been exceeded. If the slave SQL thread stops while MASTER_POS_WAIT() is waiting, the function returns NULL. If the slave is past the specified position, the function returns immediately.

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 connection_name is used when you are using multi-source-replication. If you don't specify it, it's set to the value of the default_master_connection system variable.

Statements using the MASTER_POS_WAIT() function are not safe for replication.