MySQL 5.7 Reference Manual Including MySQL NDB Cluster 7.5 and NDB Cluster 7.6
These views display which sessions are blocked waiting on metadata locks, and what is blocking them.
The column descriptions here are brief. For additional
information, see the description of the Performance Schema
metadata_locks table at
Section 25.12.12.1, “The metadata_locks Table”.
The schema_table_lock_waits and
x$schema_table_lock_waits views
have these columns:
object_schema
The schema containing the object to be locked.
object_name
The name of the instrumented object.
waiting_thread_id
The thread ID of the thread that is waiting for the lock.
waiting_pid
The processlist ID of the thread that is waiting for the lock.
waiting_account
The account associated with the session that is waiting for the lock.
waiting_lock_type
The type of the waiting lock.
waiting_lock_duration
How long the waiting lock has been waiting.
waiting_query
The statement that is waiting for the lock.
waiting_query_secs
How long the statement has been waiting, in seconds.
waiting_query_rows_affected
The number of rows affected by the statement.
waiting_query_rows_examined
The number of rows read from storage engines by the statement.
blocking_thread_id
The thread ID of the thread that is blocking the waiting lock.
blocking_pid
The processlist ID of the thread that is blocking the waiting lock.
blocking_account
The account associated with the thread that is blocking the waiting lock.
blocking_lock_type
The type of lock that is blocking the waiting lock.
blocking_lock_duration
How long the blocking lock has been held.
sql_kill_blocking_query
The KILL statement to
execute to kill the blocking statement.
sql_kill_blocking_connection
The KILL statement to
execute to kill the session running the blocking
statement.