Information Schema INNODB_SYS_SEMAPHORE_WAITS Table

MariaDB starting with 10.1.3

The Information Schema INNODB_SYS_SEMAPHORE_WAITS table is meant to contain information about current semaphore waits. At present it is not correctly populated. See MDEV-21330.

The PROCESS privilege is required to view the table.

It contains the following columns:

ColumnDescription
THREAD_IDThread id waiting for semaphore
OBJECT_NAMESemaphore name
FILEFile name where semaphore was requested
LINELine number on above file
WAIT_TIMEWait time
WAIT_OBJECT
WAIT_TYPEObject type (mutex, rw-lock)
HOLDER_THREAD_IDHolder thread id
HOLDER_FILEFile name where semaphore was acquired
HOLDER_LINELine number for above
CREATED_FILECreation file name
CREATED_LINELine number for above
WRITER_THREADLast write request thread id
RESERVATION_MODEReservation mode (shared, exclusive)
READERSNumber of readers if only shared mode
WAITERS_FLAGFlags
LOCK_WORDLock word (for developers)
LAST_READER_FILERemoved
LAST_READER_LINERemoved
LAST_WRITER_FILELast writer file name
LAST_WRITER_LINEAbove line number
OS_WAIT_COUNTWait count

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