Wait Type LCK_M_SCH_M

The wait type LCK_M_SCH_M is ranked #23 by Stedman Solutions and Database Health Monitor.

Wait statistics, in the context of SQL Server, refer to the amount of time that a query spends waiting to access data in the database. When a client application requests data from the database, the request is placed in a queue and the client application must wait for its turn to access the data. The time that the query spends waiting is called a "wait" and is tracked by SQL Server. This information can be used to identify potential performance bottlenecks and optimize the performance of the database. Wait statistics are commonly used by database administrators to diagnose and troubleshoot performance issues in SQL Server.


The LCK_M_SCH_M wait type in SQL Server is a type of wait that occurs when a task is waiting to acquire a schema modification lock. In SQL Server, a schema modification lock is a type of lock that is used to protect the structure of an object, such as a table or index, during certain operations. For example, a schema modification lock might be taken when a query is modifying the structure of an object, or when an index is being created. When a task is in the LCK_M_SCH_M wait state, it is waiting for the schema modification lock to be released before it can continue execution. This wait type is typically only seen when certain operations are being performed on an object in the database.

Applies to

Related Waits

LCK_M_BU
LCK_M_BU_ABORT_BLOCKERS
LCK_M_BU_LOW_PRIORITY
LCK_M_IS
LCK_M_IS_ABORT_BLOCKERS
LCK_M_IS_LOW_PRIORITY
LCK_M_IU
LCK_M_IU_ABORT_BLOCKERS
LCK_M_IU_LOW_PRIORITY
LCK_M_IX
LCK_M_IX_ABORT_BLOCKERS
LCK_M_IX_LOW_PRIORITY
LCK_M_RIn_NL
LCK_M_RIn_NL_ABORT_BLOCKERS
LCK_M_RIn_NL_LOW_PRIORITY
LCK_M_RIn_S
LCK_M_RIn_S_ABORT_BLOCKERS
LCK_M_RIn_S_LOW_PRIORITY
LCK_M_RIn_U
LCK_M_RIn_U_ABORT_BLOCKERS
LCK_M_RIn_U_LOW_PRIORITY
LCK_M_RIn_X
LCK_M_RIn_X_ABORT_BLOCKERS
LCK_M_RIn_X_LOW_PRIORITY
LCK_M_RS_S
LCK_M_RS_S_ABORT_BLOCKERS
LCK_M_RS_S_LOW_PRIORITY
LCK_M_RS_U
LCK_M_RS_U_ABORT_BLOCKERS
LCK_M_RS_U_LOW_PRIORITY
LCK_M_RX_S
LCK_M_RX_S_ABORT_BLOCKERS
LCK_M_RX_S_LOW_PRIORITY
LCK_M_RX_U
LCK_M_RX_U_ABORT_BLOCKERS
LCK_M_RX_U_LOW_PRIORITY
LCK_M_RX_X
LCK_M_RX_X_ABORT_BLOCKERS
LCK_M_RX_X_LOW_PRIORITY
LCK_M_S
LCK_M_S_ABORT_BLOCKERS
LCK_M_S_LOW_PRIORITY
LCK_M_SCH_M_ABORT_BLOCKERS
LCK_M_SCH_M_LOW_PRIORITY
LCK_M_SCH_S
LCK_M_SCH_S_ABORT_BLOCKERS
LCK_M_SCH_S_LOW_PRIORITY
LCK_M_SIU
LCK_M_SIU_ABORT_BLOCKERS
LCK_M_SIU_LOW_PRIORITY
LCK_M_SIX
LCK_M_SIX_ABORT_BLOCKERS
LCK_M_SIX_LOW_PRIORITY
LCK_M_U
LCK_M_U_ABORT_BLOCKERS
LCK_M_U_LOW_PRIORITY
LCK_M_UIX
LCK_M_UIX_ABORT_BLOCKERS
LCK_M_UIX_LOW_PRIORITY
LCK_M_X
LCK_M_X_ABORT_BLOCKERS
LCK_M_X_LOW_PRIORITY

See Also


All Wait Types