Wait Type Reference

Wait Type	Category	Version	Description	Action
ASYNC_IO_COMPLETION	Other Disk IO	>= 2005	Occurs when a task is waiting for I/Os to finish.	Since this is used for various reason you need to find out what query or task is associated with the wait. Two examples of where this wait type is used is to create files associated with a CREATE DATABASE and for “zeroing” out a transaction log file during log creation or growth.
ASYNC_NETWORK_IO	Network IO		Occurs on network writes when the task is blocked behind the network. Verify that the client is processing data from the server.
BACKUPIO	Other Disk IO		Occurs when a backup task is waiting for data, or is waiting for a buffer in which to store data. This type is not typical, except when a task is waiting for a tape mount.
BROKER_CONNECTION_RECEIVE_TASK	Service Broker		Occurs when waiting for access to receive a message on a connection endpoint. Receive access to the endpoint is serialized.
BROKER_DISPATCHER	Service Broker
BROKER_ENDPOINT_STATE_MUTEX	Service Broker		Occurs when there is contention to access the state of a Service Broker connection endpoint. Access to the state for changes is serialized.
BROKER_EVENTHANDLER	Service Broker		Occurs when a task is waiting in the primary event handler of the Service Broker. This should occur very briefly.
BROKER_FORWARDER	Service Broker
BROKER_INIT	Service Broker		Occurs when initializing Service Broker in each active database. This should occur infrequently.
BROKER_MASTERSTART	Service Broker		Occurs when a task is waiting for the primary event handler of the Service Broker to start. This should occur very briefly.
BROKER_RECEIVE_WAITFOR	User Wait		Occurs when the RECEIVE WAITFOR is waiting. This is typical if no messages are ready to be received.
BROKER_REGISTERALLENDPOINTS	Service Broker		Occurs during the initialization of a Service Broker connection endpoint. This should occur very briefly.
BROKER_SERVICE	Service Broker		Occurs when the Service Broker destination list that is associated with a target service is updated or re-prioritized.
BROKER_SHUTDOWN	Service Broker		Occurs when there is a planned shutdown of Service Broker. This should occur very briefly, if at all.
BROKER_START	Service Broker
BROKER_TASK_SHUTDOWN	Service Broker
BROKER_TASK_STOP	Service Broker		Occurs when the Service Broker queue task handler tries to shut down the task. The state check is serialized and must be in a running state beforehand.
BROKER_TASK_SUBMIT	Service Broker
BROKER_TO_FLUSH	Service Broker		Occurs when the Service Broker lazy flusher flushes the in-memory transmission objects to a work table.
BROKER_TRANSMISSION_OBJECT	Service Broker
BROKER_TRANSMISSION_TABLE	Service Broker
BROKER_TRANSMISSION_WORK	Service Broker
BROKER_TRANSMITTER	Service Broker		Occurs when the Service Broker transmitter is waiting for work.
CHECKPOINT_QUEUE	Idle	>= 2008	Occurs while the checkpoint task is waiting for the next checkpoint request.	You should be able to safely ignore this one as it is just indicates the checkpoint background worker is waiting for work to do. I suppose if you thought you had issues with checkpoints not working or log truncation you might see if this worker ever “wakes up”. Expect higher wait times as this will only wake up when work to do
CHKPT	Tran Log IO	>= 2005	Occurs at server startup to tell the checkpoint thread that it can start.	You should be able to safely ignore. You should see 1 wait of this type for the server unless the checkpoint worker crashed and had to be restarted.. If though this is technically a “sync” type of event I left its usage as Background
CLR_AUTO_EVENT	SQL CLR		Occurs when a task is currently performing common language runtime (CLR) execution and is waiting for a particular autoevent to be initiated. Long waits are typical, and do not indicate a problem.
CLR_CRST	SQL CLR		Occurs when a task is currently performing CLR execution and is waiting to enter a critical section of the task that is currently being used by another task.
CLR_JOIN	SQL CLR		Occurs when a task is currently performing CLR execution and waiting for another task to end. This wait state occurs when there is a join between tasks.
CLR_MANUAL_EVENT	SQL CLR		Occurs when a task is currently performing CLR execution and is waiting for a specific manual event to be initiated.
CLR_MEMORY_SPY	SQL CLR		Occurs during a wait on lock acquisition for a data structure that is used to record all virtual memory allocations that come from CLR. The data structure is locked to maintain its integrity if there is parallel access.
CLR_MONITOR	SQL CLR		Occurs when a task is currently performing CLR execution and is waiting to obtain a lock on the monitor.
CLR_RWLOCK_READER	SQL CLR		Occurs when a task is currently performing CLR execution and is waiting for a reader lock.
CLR_RWLOCK_WRITER	SQL CLR		Occurs when a task is currently performing CLR execution and is waiting for a writer lock.
CLR_SEMAPHORE	SQL CLR		Occurs when a task is currently performing CLR execution and is waiting for a semaphore.
CLR_TASK_START	SQL CLR		Occurs while waiting for a CLR task to complete startup.
CLRHOST_STATE_ACCESS	SQL CLR		Occurs where there is a wait to acquire exclusive access to the CLR-hosting data structures. This wait type occurs while setting up or tearing down the CLR runtime.
CMEMPARTITIONED	Memory
CMEMTHREAD	Memory		Occurs when a task is waiting on a thread-safe memory object. The wait time might increase when there is contention caused by multiple tasks trying to allocate memory from the same memory object.
CXPACKET	Parallelism	>= 2005	Occurs with parallel query plans when trying to synchronize the query processor exchange iterator. If waiting is excessive and cannot be reduced by tuning the query (such as adding indexes), consider adjusting the cost threshold for parallelism or lowering the degree of parallelism.	You may not need to take any action. If you see high wait times then it means you have a long running parallel query. I would first identify the query and determine if you need to tune it. Note sys.dm_exec_requests only shows the wait type of the request even if multiple tasks have different wait types. When you see CXPACKET here look at all tasks associated with the request. Find the task that doesn’t have this wait_type and see its status. It may be waiting on something else slowing down the query. wait_resource also has interesting details about the tasks and its parallel query operator
DBMIRROR_DBM_EVENT	Mirroring		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
DBMIRROR_DBM_MUTEX	Mirroring		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
DBMIRROR_EVENTS_QUEUE	Mirroring		Occurs when database mirroring waits for events to process.
DBMIRROR_SEND	Mirroring		Occurs when a task is waiting for a communications backlog at the network layer to clear to be able to send messages. Indicates that the communications layer is starting to become overloaded and affect the database mirroring data throughput.
DBMIRROR_WORKER_QUEUE	Mirroring		Indicates that the database mirroring worker task is waiting for more work.
DBMIRRORING_CMD	Mirroring		Occurs when a task is waiting for log records to be flushed to disk. This wait state is expected to be held for long periods of time.
DTC	Transaction		Occurs when a task is waiting on an event that is used to manage state transition. This state controls when the recovery of Microsoft Distributed Transaction Coordinator (MS DTC) transactions occurs after SQL Server receives notification that the MS DTC service has become unavailable. This state also describes a task that is waiting when a commit of a MS DTC transaction is initiated by SQL Server and SQL Server is waiting for the MS DTC commit to finish.
DTC_ABORT_REQUEST	Transaction		Occurs in a MS DTC worker session when the session is waiting to take ownership of a MS DTC transaction. After MS DTC owns the transaction, the session can roll back the transaction. Generally, the session will wait for another session that is using the transaction.
DTC_RESOLVE	Transaction		Occurs when a recovery task is waiting for the master database in a cross-database transaction so that the task can query the outcome of the transaction.
DTC_STATE	Transaction		Occurs when a task is waiting on an event that protects changes to the internal MS DTC global state object. This state should be held for very short periods of time.
DTC_TMDOWN_REQUEST	Transaction		Occurs in a MS DTC worker session when SQL Server receives notification that the MS DTC service is not available. First, the worker will wait for the MS DTC recovery process to start. Then, the worker waits to obtain the outcome of the distributed transaction that the worker is working on. This may continue until the connection with the MS DTC service has been reestablished.
DTC_WAITFOR_OUTCOME	Transaction		Occurs when recovery tasks wait for MS DTC to become active to enable the resolution of prepared transactions.
DTCNEW_ENLIST	Transaction
DTCNEW_PREPARE	Transaction
DTCNEW_RECOVERY	Transaction
DTCNEW_TM	Transaction
DTCNEW_TRANSACTION_ENLISTMENT	Transaction
DTCPNTSYNC	Transaction
EE_PMOLOCK	Memory		Occurs during synchronization of certain types of memory allocations during statement execution.
EXCHANGE	Parallelism		Occurs during synchronization in the query processor exchange iterator during parallel queries.
EXTERNAL_SCRIPT_NETWORK_IOF	Network IO
FCB_REPLICA_READ	Replication		Occurs when the reads of a snapshot (or a temporary snapshot created by DBCC) sparse file are synchronized.
FCB_REPLICA_WRITE	Replication		Occurs when the pushing or pulling of a page to a snapshot (or a temporary snapshot created by DBCC) sparse file is synchronized.
FT_COMPROWSET_RWLOCK	Full Text Search		Full-text is waiting on fragment metadata operation. Documented for informational purposes only. Not supported. Future compatibility is not guaranteed.
FT_IFTS_RWLOCK	Full Text Search		Full-text is waiting on internal synchronization. Documented for informational purposes only. Not supported. Future compatibility is not guaranteed.
FT_IFTS_SCHEDULER_IDLE_WAIT	Idle	>= 2008	Full-text scheduler sleep wait type. The scheduler is idle.	You should be able to safely ignore unless some unexplained FTS issue. High wait times are normal
FT_IFTSHC_MUTEX	Full Text Search		Full-text is waiting on an fdhost control operation. Documented for informational purposes only. Not supported. Future compatibility is not guaranteed.
FT_IFTSISM_MUTEX	Full Text Search		Full-text is waiting on communication operation. Documented for informational purposes only. Not supported. Future compatibility is not guaranteed.
FT_MASTER_MERGE	Full Text Search		Full-text is waiting on master merge operation. Documented for informational purposes only. Not supported. Future compatibility is not guaranteed.
FT_MASTER_MERGE_COORDINATOR	Full Text Search
FT_METADATA_MUTEX	Full Text Search		Documented for informational purposes only. Not supported. Future compatibility is not guaranteed.
FT_PROPERTYLIST_CACHE	Full Text Search
FT_RESTART_CRAWL	Full Text Search		Occurs when a full-text crawl needs to restart from a last known good point to recover from a transient failure. The wait lets the worker tasks currently working on that population to complete or exit the current step.
FULLTEXT GATHERER	Full Text Search		Occurs during synchronization of full-text operations.
HADR_AG_MUTEX	Replication		Occurs when an AlwaysOn DDL statement or Windows Server Failover Clustering command is waiting for exclusive read/write access to the configuration of an availability group.
HADR_AR_CRITICAL_SECTION_ENTRY	Replication		Occurs when an AlwaysOn DDL statement or Windows Server Failover Clustering command is waiting for exclusive read/write access to the runtime state of the local replica of the associated availability group.
HADR_AR_MANAGER_MUTEX	Replication		Occurs when an availability replica shutdown is waiting for startup to complete or an availability replica startup is waiting for shutdown to complete. Internal use only. Availability replica shutdown is initiated either by SQL Server shutdown or by SQL Server handling the loss of quorum by the Windows Server Failover Clustering node. Availability replica startup is initiated either by SQL Server startup or by SQL Server recovering from the loss of quorum by the Windows Server Failover Clustering node.
HADR_AR_UNLOAD_COMPLETED	Replication
HADR_ARCONTROLLER_NOTIFICATIONS_SUBSCRIBER_LIST	Replication		The publisher for an availability replica event (such as a state change or configuration change) is waiting for exclusive read/write access to the list of event subscribers. Internal use only.
HADR_BACKUP_BULK_LOCK	Replication		The AlwaysOn primary database received a backup request from a secondary database and is waiting for the background thread to finish processing the request on acquiring or releasing the BulkOp lock.
HADR_BACKUP_QUEUE	Replication		The backup background thread of the AlwaysOn primary database is waiting for a new work request from the secondary database. (typically, this occurs when the primary database is holding the BulkOp log and is waiting for the secondary database to indicate that the primary database can release the lock).
HADR_CLUSAPI_CALL	Replication		A SQL Server thread is waiting to switch from non-preemptive mode (scheduled by SQL Server) to preemptive mode (scheduled by the operating system) in order to invoke Windows Server Failover Clustering APIs.
HADR_COMPRESSED_CACHE_SYNC	Replication		Waiting for access to the cache of compressed log blocks that is used to avoid redundant compression of the log blocks sent to multiple secondary databases.
HADR_CONNECTIVITY_INFO	Replication
HADR_DATABASE_FLOW_CONTROL	Replication		Waiting for messages to be sent to the partner when the maximum number of queued messages has been reached. Indicates that the log scans are running faster than the network sends. This is an issue only if network sends are slower than expected.
HADR_DATABASE_VERSIONING_STATE	Replication		Occurs on the versioning state change of an AlwaysOn secondary database. This wait is for internal data structures and is usually is very short with no direct effect on data access.
HADR_DATABASE_WAIT_FOR_RECOVERY	Replication
HADR_DATABASE_WAIT_FOR_RESTART	Replication		Waiting for the database to restart under AlwaysOn Availability Groups control. Under normal conditions, this is not a customer issue because waits are expected here.
HADR_DATABASE_WAIT_FOR_TRANSITION_TO_VERSIONING	Replication		A query on object(s) in a readable secondary database of an AlwaysOn availability group is blocked on row versioning while waiting for commit or rollback of all transactions that were in-flight when the secondary replica was enabled for read workloads. This wait type guarantees that row versions are available before execution of a query under snapshot isolation.
HADR_DB_COMMAND	Replication		Waiting for responses to conversational messages (which require an explicit response from the other side, using the AlwaysOn conversational message infrastructure). A number of different message types use this wait type.
HADR_DB_OP_COMPLETION_SYNC	Replication		Waiting for responses to conversational messages (which require an explicit response from the other side, using the AlwaysOn conversational message infrastructure). A number of different message types use this wait type.
HADR_DB_OP_START_SYNC	Replication		An AlwaysOn DDL statement or a Windows Server Failover Clustering command is waiting for serialized access to an availability database and its runtime state.
HADR_DBR_SUBSCRIBER	Replication		The publisher for an availability replica event (such as a state change or configuration change) is waiting for exclusive read/write access to the runtime state of an event subscriber that corresponds to an availability database. Internal use only.
HADR_DBR_SUBSCRIBER_FILTER_LIST	Replication		The publisher for an availability replica event (such as a state change or configuration change) is waiting for exclusive read/write access to the list of event subscribers that correspond to availability databases. Internal use only.
HADR_DBSEEDING	Replication
HADR_DBSEEDING_LIST	Replication
HADR_DBSTATECHANGE_SYNC	Replication		Concurrency control wait for updating the internal state of the database replica.
HADR_FABRIC_CALLBACK	Replication
HADR_FILESTREAM_BLOCK_FLUSH	Replication		The FILESTREAM AlwaysOn transport manager is waiting until processing of a log block is finished.
HADR_FILESTREAM_FILE_CLOSE	Replication		The FILESTREAM AlwaysOn transport manager is waiting until the next FILESTREAM file gets processed and its handle gets closed.
HADR_FILESTREAM_FILE_REQUEST	Replication		An AlwaysOn secondary replica is waiting for the primary replica to send all requested FILESTREAM files during UNDO.
HADR_FILESTREAM_IOMGR	Replication		The FILESTREAM AlwaysOn transport manager is waiting for R/W lock that protects the FILESTREAM AlwaysOn I/O manager during startup or shutdown.
HADR_FILESTREAM_IOMGR_IOCOMPLETION	Replication		The FILESTREAM AlwaysOn I/O manager is waiting for I/O completion.
HADR_FILESTREAM_MANAGER	Replication		The FILESTREAM AlwaysOn transport manager is waiting for the R/W lock that protects the FILESTREAM AlwaysOn transport manager during startup or shutdown.
HADR_FILESTREAM_PREPROC	Replication
HADR_GROUP_COMMIT	Replication		Transaction commit processing is waiting to allow a group commit so that multiple commit log records can be put into a single log block. This wait is an expected condition that optimizes the log I/O, capture, and send operations.
HADR_LOGCAPTURE_SYNC	Replication		Concurrency control around the log capture or apply object when creating or destroying scans. This is an expected wait when partners change state or connection status.
HADR_LOGCAPTURE_WAIT	Replication		Waiting for log records to become available. Can occur either when waiting for new log records to be generated by connections or for I/O completion when reading log not in the cache. This is an expected wait if the log scan is caught up to the end of log or is reading from disk.
HADR_LOGPROGRESS_SYNC	Replication		Concurrency control wait when updating the log progress status of database replicas.
HADR_NOTIFICATION_DEQUEUE	Replication		A background task that processes Windows Server Failover Clustering notifications is waiting for the next notification. Internal use only.
HADR_NOTIFICATION_WORKER_EXCLUSIVE_ACCESS	Replication		The AlwaysOn availability replica manager is waiting for serialized access to the runtime state of a background task that processes Windows Server Failover Clustering notifications. Internal use only.
HADR_NOTIFICATION_WORKER_STARTUP_SYNC	Replication		A background task is waiting for the completion of the startup of a background task that processes Windows Server Failover Clustering notifications. Internal use only.
HADR_NOTIFICATION_WORKER_TERMINATION_SYNC	Replication		A background task is waiting for the termination of a background task that processes Windows Server Failover Clustering notifications. Internal use only.
HADR_PARTNER_SYNC	Replication		Concurrency control wait on the partner list.
HADR_READ_ALL_NETWORKS	Replication		Waiting to get read or write access to the list of WSFC networks. Internal use only. The engine keeps a list of WSFC networks that is used in dynamic management views (such as sys.dm_hadr_cluster_networks) or to validate AlwaysOn Transact-SQL statements that reference WSFC network information. This list is updated upon engine startup, WSFC related notifications, and internal AlwaysOn restart (for example, losing and regaining of WSFC quorum). Tasks will usually be blocked when an update in that list is in progress.
HADR_RECOVERY_WAIT_FOR_CONNECTION	Replication		Waiting for the secondary database to connect to the primary database before running recovery. This is an expected wait, which can lengthen if the connection to the primary is slow to establish.
HADR_RECOVERY_WAIT_FOR_UNDO	Replication		Database recovery is waiting for the secondary database to finish the reverting and initializing phase to bring it back to the common log point with the primary database. This is an expected wait after failovers.Undo progress can be tracked through the Windows System Monitor (perfmon.exe) and dynamic management views.
HADR_REPLICAINFO_SYNC	Replication		Waiting for concurrency control to update the current replica state.
HADR_SEEDING_CANCELLATION	Replication
HADR_SEEDING_FILE_LIST	Replication
HADR_SEEDING_LIMIT_BACKUPS	Replication
HADR_SEEDING_SYNC_COMPLETION	Replication
HADR_SEEDING_TIMEOUT_TASK	Replication
HADR_SEEDING_WAIT_FOR_COMPLETION	Replication
HADR_SYNC_COMMIT	Replication		Waiting for transaction commit processing for the synchronized secondary databases to harden the log. This wait is also reflected by the Transaction Delay performance counter. This wait type is expected for synchronized availability groups and indicates the time to send, write, and acknowledge log to the secondary databases.
HADR_SYNCHRONIZING_THROTTLE	Replication		Waiting for transaction commit processing to allow a synchronizing secondary database to catch up to the primary end of log in order to transition to the synchronized state. This is an expected wait when a secondary database is catching up.
HADR_TDS_LISTENER_SYNC	Replication		Either the internal AlwaysOn system or the WSFC cluster will request that listeners are started or stopped. The processing of this request is always asynchronous, and there is a mechanism to remove redundant requests. There are also moments that this process is suspended because of configuration changes. All waits related with this listener synchronization mechanism use this wait type. Internal use only.
HADR_TDS_LISTENER_SYNC_PROCESSING	Replication		Used at the end of an AlwaysOn Transact-SQL statement that requires starting and/or stopping an availability group listener. Since the start/stop operation is done asynchronously, the user thread will block using this wait type until the situation of the listener is known.
HADR_THROTTLE_LOG_RATE_GOVERNOR	Log Rate Governor
HADR_TIMER_TASK	Replication		Waiting to get the lock on the timer task object and is also used for the actual waits between times that work is being performed. For example, for a task that runs every 10 seconds, after one execution, AlwaysOn Availability Groups waits about 10 seconds to reschedule the task, and the wait is included here.
HADR_TRANSPORT_DBRLIST	Replication		Waiting for access to the transport layers database replica list. Used for the spinlock that grants access to it.
HADR_TRANSPORT_FLOW_CONTROL	Replication		Waiting when the number of outstanding unacknowledged AlwaysOn messages is over the out flow control threshold. This is on an availability replica-to-replica basis (not on a database-to-database basis).
HADR_TRANSPORT_SESSION	Replication		AlwaysOn Availability Groups is waiting while changing or accessing the underlying transport state.
HADR_WORK_POOL	Replication		Concurrency control wait on the AlwaysOn Availability Groups background work task object.
HADR_WORK_QUEUE	Replication		AlwaysOn Availability Groups background worker thread waiting for new work to be assigned. This is an expected wait when there are ready workers waiting for new work, which is the normal state.
HADR_XRF_STACK_ACCESS	Replication		Accessing (look up, add, and delete) the extended recovery fork stack for an AlwaysOn availability database.
INSTANCE_LOG_RATE_GOVERNOR	Log Rate Governor
IOCOMPLETION	Other Disk IO	>= 2005	Occurs while waiting for I/O operations to complete. This wait type generally represents non-data page I/Os. Data page I/O completion waits appear as PAGEIOLATCH* waits.	If wait times are high then you have a disk I/O bottleneck. The problem will be determining what type of operation and where the bottleneck exists. For sorts, it is on the storage system associated with tempdb. Note that database page I/O does not use this wait type. Instead look at PAGEIOLATCH waits.
IO_QUEUE_LIMIT	Other Disk IO
IO_RETRY	Other Disk IO		Occurs when an I/O operation such as a read or a write to disk fails because of insufficient resources, and is then retried.
LATCHDT	Latch		Occurs when waiting for a DT (destroy) latch. This does not include buffer latches or transaction mark latches. A listing of LATCH* waits is available in sys.dm_os_latch_stats. Note that sys.dm_os_latch_stats groups LATCH_NL, LATCH_SH, LATCH_UP, LATCH_EX, and LATCH_DT waits together.
LATCHEX	Latch		Occurs when waiting for an EX (exclusive) latch. This does not include buffer latches or transaction mark latches. A listing of LATCH* waits is available in sys.dm_os_latch_stats. Note that sys.dm_os_latch_stats groups LATCH_NL, LATCH_SH, LATCH_UP, LATCH_EX, and LATCH_DT waits together.
LATCHKP	Latch		Occurs when waiting for a KP (keep) latch. This does not include buffer latches or transaction mark latches. A listing of LATCH* waits is available in sys.dm_os_latch_stats. Note that sys.dm_os_latch_stats groups LATCH_NL, LATCH_SH, LATCH_UP, LATCH_EX, and LATCH_DT waits together.
LATCH_NL	Latch		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
LATCHSH	Latch		Occurs when waiting for an SH (share) latch. This does not include buffer latches or transaction mark latches. A listing of LATCH* waits is available in sys.dm_os_latch_stats. Note that sys.dm_os_latch_stats groups LATCH_NL, LATCH_SH, LATCH_UP, LATCH_EX, and LATCH_DT waits together.
LATCHUP	Latch		Occurs when waiting for an UP (update) latch. This does not include buffer latches or transaction mark latches. A listing of LATCH* waits is available in sys.dm_os_latch_stats. Note that sys.dm_os_latch_stats groups LATCH_NL, LATCH_SH, LATCH_UP, LATCH_EX, and LATCH_DT waits together.
LAZYWRITER_SLEEP	Idle	>= 2005	Occurs when lazywriter tasks are suspended. This is a measure of the time spent by background tasks that are waiting. Do not consider this state when you are looking for user stalls.	You should be able to safely ignore this one. The wait times will appear to “cycle” as LazyWriter is designed to sleep and wake-up every 1 second. Appears as LZW_SLEEP in Xevent
LCK_M_BU	Lock		Occurs when a task is waiting to acquire a Bulk Update (BU) lock.
LCK_M_BU_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Bulk Update (BU) lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_BU_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Bulk Update (BU) lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_IS	Lock		Occurs when a task is waiting to acquire an Intent Shared (IS) lock.
LCK_M_IS_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Intent Shared (IS) lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_IS_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Intent Shared (IS) lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_IU	Lock		Occurs when a task is waiting to acquire an Intent Update (IU) lock.
LCK_M_IU_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Intent Update (IU) lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_IU_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Intent Update (IU) lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_IX	Lock		Occurs when a task is waiting to acquire an Intent Exclusive (IX) lock.
LCK_M_IX_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Intent Exclusive (IX) lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_IX_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Intent Exclusive (IX) lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_NL	Lock		Occurs when a task is waiting to acquire a lock on the current key value, and an Insert Range lock between the current and previous key. A lock on the key is an instant release lock.
LCK_M_RIn_NL_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a lock with Abort Blockers on the current key value, and an Insert Range lock with Abort Blockers between the current and previous key. A lock on the key is an instant release lock. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_NL_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a lock with Low Priority on the current key value, and an Insert Range lock with Low Priority between the current and previous key. A lock on the key is an instant release lock. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_S	Lock		Occurs when a task is waiting to acquire a shared lock on the current key value, and an Insert Range lock between the current and previous key.
LCK_M_RIn_S_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a shared lock with Abort Blockers on the current key value, and an Insert Range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_S_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a shared lock with Low Priority on the current key value, and an Insert Range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_U	Lock		Task is waiting to acquire an Update lock on the current key value, and an Insert Range lock between the current and previous key.
LCK_M_RIn_U_ABORT_BLOCKERS	Lock		Task is waiting to acquire an Update lock with Abort Blockers on the current key value, and an Insert Range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_U_LOW_PRIORITY	Lock		Task is waiting to acquire an Update lock with Low Priority on the current key value, and an Insert Range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_X	Lock		Occurs when a task is waiting to acquire an Exclusive lock on the current key value, and an Insert Range lock between the current and previous key.
LCK_M_RIn_X_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Exclusive lock with Abort Blockers on the current key value, and an Insert Range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RIn_X_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Exclusive lock with Low Priority on the current key value, and an Insert Range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RS_S	Lock		Occurs when a task is waiting to acquire a Shared lock on the current key value, and a Shared Range lock between the current and previous key.
LCK_M_RS_S_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Shared lock with Abort Blockers on the current key value, and a Shared Range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RS_S_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Shared lock with Low Priority on the current key value, and a Shared Range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RS_U	Lock		Occurs when a task is waiting to acquire an Update lock on the current key value, and an Update Range lock between the current and previous key.
LCK_M_RS_U_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Update lock with Abort Blockers on the current key value, and an Update Range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RS_U_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Update lock with Low Priority on the current key value, and an Update Range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RX_S	Lock		Occurs when a task is waiting to acquire a Shared lock on the current key value, and an Exclusive Range lock between the current and previous key.
LCK_M_RX_S_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Shared lock with Abort Blockers on the current key value, and an Exclusive Range with Abort Blockers lock between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RX_S_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Shared lock with Low Priority on the current key value, and an Exclusive Range with Low Priority lock between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RX_U	Lock		Occurs when a task is waiting to acquire an Update lock on the current key value, and an Exclusive range lock between the current and previous key.
LCK_M_RX_U_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Update lock with Abort Blockers on the current key value, and an Exclusive range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RX_U_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Update lock with Low Priority on the current key value, and an Exclusive range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RX_X	Lock		Occurs when a task is waiting to acquire an Exclusive lock on the current key value, and an Exclusive Range lock between the current and previous key.
LCK_M_RX_X_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Exclusive lock with Abort Blockers on the current key value, and an Exclusive Range lock with Abort Blockers between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_RX_X_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Exclusive lock with Low Priority on the current key value, and an Exclusive Range lock with Low Priority between the current and previous key. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_S	Lock		Occurs when a task is waiting to acquire a Shared lock.
LCK_M_S_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Shared lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_S_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Shared lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SCH_M	Lock		Occurs when a task is waiting to acquire a Schema Modify lock.
LCK_M_SCH_M_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Schema Modify lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SCH_M_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Schema Modify lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SCH_S	Lock		Occurs when a task is waiting to acquire a Schema Share lock.
LCK_M_SCH_S_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Schema Share lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SCH_S_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Schema Share lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SIU	Lock		Occurs when a task is waiting to acquire a Shared With Intent Update lock.
LCK_M_SIU_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Shared With Intent Update lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SIU_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Shared With Intent Update lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SIX	Lock		Occurs when a task is waiting to acquire a Shared With Intent Exclusive lock.
LCK_M_SIX_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire a Shared With Intent Exclusive lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_SIX_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire a Shared With Intent Exclusive lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_U	Lock		Occurs when a task is waiting to acquire an Update lock.
LCK_M_U_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Update lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_U_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Update lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_UIX	Lock		Occurs when a task is waiting to acquire an Update With Intent Exclusive lock.
LCK_M_UIX_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Update With Intent Exclusive lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_UIX_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Update With Intent Exclusive lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_X	Lock		Occurs when a task is waiting to acquire an Exclusive lock.
LCK_M_X_ABORT_BLOCKERS	Lock		Occurs when a task is waiting to acquire an Exclusive lock with Abort Blockers. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LCK_M_X_LOW_PRIORITY	Lock		Occurs when a task is waiting to acquire an Exclusive lock with Low Priority. (Related to the low priority wait option of ALTER TABLE and ALTER INDEX.)
LOGBUFFER	Tran Log IO	>= 2005	Occurs when a task is waiting for space in the log buffer to store a log record. Consistently high values may indicate that the log devices cannot keep up with the amount of log being generated by the server.	This is typically a symptom of I/O bottlenecks because other workers waiting on WRITELOG will hold on to log blocks. Look for WRITERLOG waiters and if found the overall problem is I/O bottleneck on the storage system associated with the transaction log
LOGMGR	Tran Log IO		Occurs when a task is waiting for any outstanding log I/Os to finish before shutting down the log while closing the database.
LOGMGR_FLUSH	Tran Log IO		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
LOGMGR_PMM_LOG	Tran Log IO
LOGMGR_QUEUE	Idle	>= 2005	Occurs while the log writer task waits for work requests.	You should be able to safely ignore this wait type unless you believe a problem exists in processing log blocks to flush to the transaction log. This wait type is not a wait indicating I/O bottlenecks. It is only for waiting for other workers to request log block flushes. Note that on SQL Server 2005 this wait type will not show up in sys.dm_exec_requests because the Log Writer task does not show up there.
LOGMGR_RESERVE_APPEND	Tran Log IO		Occurs when a task is waiting to see whether log truncation frees up log space to enable the task to write a new log record. Consider increasing the size of the log file(s) for the affected database to reduce this wait.
MEMORY_ALLOCATION_EXT	Memory
MEMORY_GRANT_UPDATE	Memory
MSQL_XACT_MGR_MUTEX	Transaction		Occurs when a task is waiting to obtain ownership of the session transaction manager to perform a session level transaction operation.
MSQL_XACT_MUTEX	Transaction		Occurs during synchronization of transaction usage. A request must acquire the mutex before it can use the transaction.
MSSEARCH	Full Text Search		Occurs during Full-Text Search calls. This wait ends when the full-text operation completes. It does not indicate contention, but rather the duration of full-text operations.
NET_WAITFOR_PACKET	Network IO		Occurs when a connection is waiting for a network packet during a network read.
ONDEMAND_TASK_QUEUE	Idle		Occurs while a background task waits for high priority system task requests. Long wait times indicate that there have been no high priority requests to process, and should not cause concern.
PAGEIOLATCH_DT	Buffer IO		Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Destroy mode. Long waits may indicate problems with the disk subsystem.
PAGEIOLATCH_EX	Buffer IO		Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Exclusive mode. Long waits may indicate problems with the disk subsystem.
PAGEIOLATCH_KP	Buffer IO		Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Keep mode. Long waits may indicate problems with the disk subsystem.
PAGEIOLATCH_NL	Buffer IO		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PAGEIOLATCH_SH	Buffer IO		Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Shared mode. Long waits may indicate problems with the disk subsystem.
PAGEIOLATCH_UP	Buffer IO		Occurs when a task is waiting on a latch for a buffer that is in an I/O request. The latch request is in Update mode. Long waits may indicate problems with the disk subsystem.
PAGELATCH_DT	Buffer Latch		Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Destroy mode.
PAGELATCH_EX	Buffer Latch		Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Exclusive mode.
PAGELATCH_KP	Buffer Latch		Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Keep mode.
PAGELATCH_NL	Buffer Latch		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PAGELATCH_SH	Buffer Latch		Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Shared mode.
PAGELATCH_UP	Buffer Latch		Occurs when a task is waiting on a latch for a buffer that is not in an I/O request. The latch request is in Update mode.
POOL_LOG_RATE_GOVERNOR	Log Rate Governor
PREEMPTIVE_ABR	Preemptive		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PREEMPTIVE_CLOSEBACKUPMEDIA	Preemptive		Occurs when the SQLOS scheduler switches to preemptive mode to close backup media.
PREEMPTIVE_CLOSEBACKUPTAPE	Preemptive		Occurs when the SQLOS scheduler switches to preemptive mode to close a tape backup device.
PREEMPTIVE_CLOSEBACKUPVDIDEVICE	Preemptive		Occurs when the SQLOS scheduler switches to preemptive mode to close a virtual backup device.
PREEMPTIVE_CLUSAPI_CLUSTERRESOURCECONTROL	Preemptive		Occurs when the SQLOS scheduler switches to preemptive mode to perform Windows failover cluster operations.
PREEMPTIVE_COM_COCREATEINSTANCE	Preemptive		Occurs when the SQLOS scheduler switches to preemptive mode to create a COM object.
PREEMPTIVE_COM_COGETCLASSOBJECT	Preemptive
PREEMPTIVE_COM_CREATEACCESSOR	Preemptive
PREEMPTIVE_COM_DELETEROWS	Preemptive
PREEMPTIVE_COM_GETCOMMANDTEXT	Preemptive
PREEMPTIVE_COM_GETDATA	Preemptive
PREEMPTIVE_COM_GETNEXTROWS	Preemptive
PREEMPTIVE_COM_GETRESULT	Preemptive
PREEMPTIVE_COM_GETROWSBYBOOKMARK	Preemptive
PREEMPTIVE_COM_LBFLUSH	Preemptive
PREEMPTIVE_COM_LBLOCKREGION	Preemptive
PREEMPTIVE_COM_LBREADAT	Preemptive
PREEMPTIVE_COM_LBSETSIZE	Preemptive
PREEMPTIVE_COM_LBSTAT	Preemptive
PREEMPTIVE_COM_LBUNLOCKREGION	Preemptive
PREEMPTIVE_COM_LBWRITEAT	Preemptive
PREEMPTIVE_COM_QUERYINTERFACE	Preemptive
PREEMPTIVE_COM_RELEASE	Preemptive
PREEMPTIVE_COM_RELEASEACCESSOR	Preemptive
PREEMPTIVE_COM_RELEASEROWS	Preemptive
PREEMPTIVE_COM_RELEASESESSION	Preemptive
PREEMPTIVE_COM_RESTARTPOSITION	Preemptive
PREEMPTIVE_COM_SEQSTRMREAD	Preemptive
PREEMPTIVE_COM_SEQSTRMREADANDWRITE	Preemptive
PREEMPTIVE_COM_SETDATAFAILURE	Preemptive
PREEMPTIVE_COM_SETPARAMETERINFO	Preemptive
PREEMPTIVE_COM_SETPARAMETERPROPERTIES	Preemptive
PREEMPTIVE_COM_STRMLOCKREGION	Preemptive
PREEMPTIVE_COM_STRMSEEKANDREAD	Preemptive
PREEMPTIVE_COM_STRMSEEKANDWRITE	Preemptive
PREEMPTIVE_COM_STRMSETSIZE	Preemptive
PREEMPTIVE_COM_STRMSTAT	Preemptive
PREEMPTIVE_COM_STRMUNLOCKREGION	Preemptive
PREEMPTIVE_CONSOLEWRITE	Preemptive
PREEMPTIVE_CREATEPARAM	Preemptive
PREEMPTIVE_DEBUG	Preemptive
PREEMPTIVE_DFSADDLINK	Preemptive
PREEMPTIVE_DFSLINKEXISTCHECK	Preemptive
PREEMPTIVE_DFSLINKHEALTHCHECK	Preemptive
PREEMPTIVE_DFSREMOVELINK	Preemptive
PREEMPTIVE_DFSREMOVEROOT	Preemptive
PREEMPTIVE_DFSROOTFOLDERCHECK	Preemptive
PREEMPTIVE_DFSROOTINIT	Preemptive
PREEMPTIVE_DFSROOTSHARECHECK	Preemptive
PREEMPTIVE_DTC_ABORT	Preemptive
PREEMPTIVE_DTC_ABORTREQUESTDONE	Preemptive
PREEMPTIVE_DTC_BEGINTRANSACTION	Preemptive
PREEMPTIVE_DTC_COMMITREQUESTDONE	Preemptive
PREEMPTIVE_DTC_ENLIST	Preemptive
PREEMPTIVE_DTC_PREPAREREQUESTDONE	Preemptive
PREEMPTIVE_FILESIZEGET	Preemptive
PREEMPTIVE_FSAOLEDB_ABORTTRANSACTION	Preemptive
PREEMPTIVE_FSAOLEDB_COMMITTRANSACTION	Preemptive
PREEMPTIVE_FSAOLEDB_STARTTRANSACTION	Preemptive
PREEMPTIVE_FSRECOVER_UNCONDITIONALUNDO	Preemptive
PREEMPTIVE_GETRMINFO	Preemptive
PREEMPTIVE_HADR_LEASE_MECHANISM	Preemptive		AlwaysOn Availability Groups lease manager scheduling for CSS diagnostics.
PREEMPTIVE_HTTP_EVENT_WAIT	Preemptive
PREEMPTIVE_HTTP_REQUEST	Preemptive
PREEMPTIVE_LOCKMONITOR	Preemptive
PREEMPTIVE_MSS_RELEASE	Preemptive
PREEMPTIVE_ODBCOPS	Preemptive
PREEMPTIVE_OLE_UNINIT	Preemptive
PREEMPTIVE_OLEDB_ABORTORCOMMITTRAN	Preemptive
PREEMPTIVE_OLEDB_ABORTTRAN	Preemptive
PREEMPTIVE_OLEDB_GETDATASOURCE	Preemptive
PREEMPTIVE_OLEDB_GETLITERALINFO	Preemptive
PREEMPTIVE_OLEDB_GETPROPERTIES	Preemptive
PREEMPTIVE_OLEDB_GETPROPERTYINFO	Preemptive
PREEMPTIVE_OLEDB_GETSCHEMALOCK	Preemptive
PREEMPTIVE_OLEDB_JOINTRANSACTION	Preemptive
PREEMPTIVE_OLEDB_RELEASE	Preemptive
PREEMPTIVE_OLEDB_SETPROPERTIES	Preemptive
PREEMPTIVE_OLEDBOPS	Preemptive
PREEMPTIVE_OS_ACCEPTSECURITYCONTEXT	Preemptive
PREEMPTIVE_OS_ACQUIRECREDENTIALSHANDLE	Preemptive
PREEMPTIVE_OS_AUTHENTICATIONOPS	Preemptive
PREEMPTIVE_OS_AUTHORIZATIONOPS	Preemptive
PREEMPTIVE_OS_AUTHZGETINFORMATIONFROMCONTEXT	Preemptive
PREEMPTIVE_OS_AUTHZINITIALIZECONTEXTFROMSID	Preemptive
PREEMPTIVE_OS_AUTHZINITIALIZERESOURCEMANAGER	Preemptive
PREEMPTIVE_OS_BACKUPREAD	Preemptive
PREEMPTIVE_OS_CLOSEHANDLE	Preemptive
PREEMPTIVE_OS_CLUSTEROPS	Preemptive
PREEMPTIVE_OS_COMOPS	Preemptive
PREEMPTIVE_OS_COMPLETEAUTHTOKEN	Preemptive
PREEMPTIVE_OS_COPYFILE	Preemptive
PREEMPTIVE_OS_CREATEDIRECTORY	Preemptive
PREEMPTIVE_OS_CREATEFILE	Preemptive
PREEMPTIVE_OS_CRYPTACQUIRECONTEXT	Preemptive
PREEMPTIVE_OS_CRYPTIMPORTKEY	Preemptive
PREEMPTIVE_OS_CRYPTOPS	Preemptive
PREEMPTIVE_OS_DECRYPTMESSAGE	Preemptive
PREEMPTIVE_OS_DELETEFILE	Preemptive
PREEMPTIVE_OS_DELETESECURITYCONTEXT	Preemptive
PREEMPTIVE_OS_DEVICEIOCONTROL	Preemptive
PREEMPTIVE_OS_DEVICEOPS	Preemptive
PREEMPTIVE_OS_DIRSVC_NETWORKOPS	Preemptive
PREEMPTIVE_OS_DISCONNECTNAMEDPIPE	Preemptive
PREEMPTIVE_OS_DOMAINSERVICESOPS	Preemptive
PREEMPTIVE_OS_DSGETDCNAME	Preemptive
PREEMPTIVE_OS_DTCOPS	Preemptive
PREEMPTIVE_OS_ENCRYPTMESSAGE	Preemptive
PREEMPTIVE_OS_FILEOPS	Preemptive
PREEMPTIVE_OS_FINDFILE	Preemptive
PREEMPTIVE_OS_FLUSHFILEBUFFERS	Preemptive
PREEMPTIVE_OS_FORMATMESSAGE	Preemptive
PREEMPTIVE_OS_FREECREDENTIALSHANDLE	Preemptive
PREEMPTIVE_OS_FREELIBRARY	Preemptive
PREEMPTIVE_OS_GENERICOPS	Preemptive
PREEMPTIVE_OS_GETADDRINFO	Preemptive
PREEMPTIVE_OS_GETCOMPRESSEDFILESIZE	Preemptive
PREEMPTIVE_OS_GETDISKFREESPACE	Preemptive
PREEMPTIVE_OS_GETFILEATTRIBUTES	Preemptive
PREEMPTIVE_OS_GETFILESIZE	Preemptive
PREEMPTIVE_OS_GETFINALFILEPATHBYHANDLE	Preemptive
PREEMPTIVE_OS_GETLONGPATHNAME	Preemptive
PREEMPTIVE_OS_GETPROCADDRESS	Preemptive
PREEMPTIVE_OS_GETVOLUMENAMEFORVOLUMEMOUNTPOINT	Preemptive
PREEMPTIVE_OS_GETVOLUMEPATHNAME	Preemptive
PREEMPTIVE_OS_INITIALIZESECURITYCONTEXT	Preemptive
PREEMPTIVE_OS_LIBRARYOPS	Preemptive
PREEMPTIVE_OS_LOADLIBRARY	Preemptive
PREEMPTIVE_OS_LOGONUSER	Preemptive
PREEMPTIVE_OS_LOOKUPACCOUNTSID	Preemptive
PREEMPTIVE_OS_MESSAGEQUEUEOPS	Preemptive
PREEMPTIVE_OS_MOVEFILE	Preemptive
PREEMPTIVE_OS_NETGROUPGETUSERS	Preemptive
PREEMPTIVE_OS_NETLOCALGROUPGETMEMBERS	Preemptive
PREEMPTIVE_OS_NETUSERGETGROUPS	Preemptive
PREEMPTIVE_OS_NETUSERGETLOCALGROUPS	Preemptive
PREEMPTIVE_OS_NETUSERMODALSGET	Preemptive
PREEMPTIVE_OS_NETVALIDATEPASSWORDPOLICY	Preemptive
PREEMPTIVE_OS_NETVALIDATEPASSWORDPOLICYFREE	Preemptive
PREEMPTIVE_OS_OPENDIRECTORY	Preemptive
PREEMPTIVE_OS_PDH_WMI_INIT	Preemptive
PREEMPTIVE_OS_PIPEOPS	Preemptive
PREEMPTIVE_OS_PROCESSOPS	Preemptive
PREEMPTIVE_OS_QUERYCONTEXTATTRIBUTES	Preemptive
PREEMPTIVE_OS_QUERYREGISTRY	Preemptive
PREEMPTIVE_OS_QUERYSECURITYCONTEXTTOKEN	Preemptive
PREEMPTIVE_OS_REMOVEDIRECTORY	Preemptive
PREEMPTIVE_OS_REPORTEVENT	Preemptive
PREEMPTIVE_OS_REVERTTOSELF	Preemptive
PREEMPTIVE_OS_RSFXDEVICEOPS	Preemptive
PREEMPTIVE_OS_SECURITYOPS	Preemptive
PREEMPTIVE_OS_SERVICEOPS	Preemptive
PREEMPTIVE_OS_SETENDOFFILE	Preemptive
PREEMPTIVE_OS_SETFILEPOINTER	Preemptive
PREEMPTIVE_OS_SETFILEVALIDDATA	Preemptive
PREEMPTIVE_OS_SETNAMEDSECURITYINFO	Preemptive
PREEMPTIVE_OS_SQLCLROPS	Preemptive
PREEMPTIVE_OS_SQMLAUNCH	Preemptive
PREEMPTIVE_OS_VERIFYSIGNATURE	Preemptive
PREEMPTIVE_OS_VERIFYTRUST	Preemptive
PREEMPTIVE_OS_VSSOPS	Preemptive
PREEMPTIVE_OS_WAITFORSINGLEOBJECT	Preemptive
PREEMPTIVE_OS_WINSOCKOPS	Preemptive
PREEMPTIVE_OS_WRITEFILE	Preemptive
PREEMPTIVE_OS_WRITEFILEGATHER	Preemptive
PREEMPTIVE_OS_WSASETLASTERROR	Preemptive
PREEMPTIVE_REENLIST	Preemptive
PREEMPTIVE_RESIZELOG	Preemptive
PREEMPTIVE_ROLLFORWARDREDO	Preemptive
PREEMPTIVE_ROLLFORWARDUNDO	Preemptive
PREEMPTIVE_SB_STOPENDPOINT	Preemptive
PREEMPTIVE_SERVER_STARTUP	Preemptive
PREEMPTIVE_SETRMINFO	Preemptive
PREEMPTIVE_SHAREDMEM_GETDATA	Preemptive
PREEMPTIVE_SNIOPEN	Preemptive
PREEMPTIVE_SOSHOST	Preemptive
PREEMPTIVE_SOSTESTING	Preemptive		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PREEMPTIVE_SP_SERVER_DIAGNOSTICS	Preemptive
PREEMPTIVE_STARTRM	Preemptive
PREEMPTIVE_STREAMFCB_CHECKPOINT	Preemptive
PREEMPTIVE_STREAMFCB_RECOVER	Preemptive
PREEMPTIVE_STRESSDRIVER	Preemptive		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PREEMPTIVE_TESTING	Preemptive		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PREEMPTIVE_TRANSIMPORT	Preemptive
PREEMPTIVE_UNMARSHALPROPAGATIONTOKEN	Preemptive
PREEMPTIVE_VSS_CREATESNAPSHOT	Preemptive
PREEMPTIVE_VSS_CREATEVOLUMESNAPSHOT	Preemptive
PREEMPTIVE_XE_CALLBACKEXECUTE	Preemptive
PREEMPTIVE_XE_CX_FILE_OPEN	Preemptive
PREEMPTIVE_XE_CX_HTTP_CALL	Preemptive
PREEMPTIVE_XE_DISPATCHER	Preemptive
PREEMPTIVE_XE_ENGINEINIT	Preemptive
PREEMPTIVE_XE_GETTARGETSTATE	Preemptive
PREEMPTIVE_XE_SESSIONCOMMIT	Preemptive
PREEMPTIVE_XE_TARGETFINALIZE	Preemptive
PREEMPTIVE_XE_TARGETINIT	Preemptive
PREEMPTIVE_XE_TIMERRUN	Preemptive
PREEMPTIVE_XETESTING	Preemptive		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
PWAIT_HADR_ACTION_COMPLETED	Replication
PWAIT_HADR_CHANGE_NOTIFIER_TERMINATION_SYNC	Replication		Occurs when a background task is waiting for the termination of the background task that receives (via polling) Windows Server Failover Clustering notifications.
PWAIT_HADR_CLUSTER_INTEGRATION	Replication		An append, replace, and/or remove operation is waiting to grab a write lock on an AlwaysOn internal list (such as a list of networks, network addresses, or availability group listeners). Internal use only
PWAIT_HADR_FAILOVER_COMPLETED	Replication
PWAIT_HADR_JOIN	Replication
PWAIT_HADR_OFFLINE_COMPLETED	Replication		An AlwaysOn drop availability group operation is waiting for the target availability group to go offline before destroying Windows Server Failover Clustering objects.
PWAIT_HADR_ONLINE_COMPLETED	Replication		An AlwaysOn create or failover availability group operation is waiting for the target availability group to come online.
PWAIT_HADR_POST_ONLINE_COMPLETED	Replication		An AlwaysOn drop availability group operation is waiting for the termination of any background task that was scheduled as part of a previous command. For example, there may be a background task that is transitioning availability databases to the primary role. The DROP AVAILABILITY GROUP DDL must wait for this background task to terminate in order to avoid race conditions.
PWAIT_HADR_SERVER_READY_CONNECTIONS	Replication
PWAIT_HADR_WORKITEM_COMPLETED	Replication		Internal wait by a thread waiting for an async work task to complete. This is an expected wait and is for CSS use.
PWAIT_HADRSIM	Replication
PWAIT_RESOURCE_SEMAPHORE_FT_PARALLEL_QUERY_SYNC	Full Text Search
QUERY_TRACEOUT	Tracing		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
REPL_CACHE_ACCESS	Replication		Occurs during synchronization on a replication article cache. During these waits, the replication log reader stalls, and data definition language (DDL) statements on a published table are blocked.
REPL_HISTORYCACHE_ACCESS	Replication
REPL_SCHEMA_ACCESS	Replication		Occurs during synchronization of replication schema version information. This state exists when DDL statements are executed on the replicated object, and when the log reader builds or consumes versioned schema based on DDL occurrence. This wait type is also used by log reader agent to synchronize memory access. If a publisher has large number of very active published databases and log reader agents, contention can be seen on this wait type.
REPL_TRANFSINFO_ACCESS	Replication
REPL_TRANHASHTABLE_ACCESS	Replication
REPL_TRANTEXTINFO_ACCESS	Replication
REPLICA_WRITES	Replication		Occurs while a task waits for completion of page writes to database snapshots or DBCC replicas.
REQUEST_FOR_DEADLOCK_SEARCH	Idle	>= 2008	Occurs while the deadlock monitor waits to start the next deadlock search. This wait is expected between deadlock detections, and lengthy total waiting time on this resource does not indicate a problem.	You should be able to safely ignore this one as it is just and indication the lock monitor thread is temporarily sleeping before it wakes up to do work. This wait type should never exceed 5 seconds in one “wait” as this is the interval the lock monitor wakes up to check for deadlocks
RESERVED_MEMORY_ALLOCATION_EXT	Memory
RESOURCE_SEMAPHORE	Memory	>= 2005	Occurs when a query memory request cannot be granted immediately due to other concurrent queries. High waits and wait times may indicate excessive number of concurrent queries, or excessive memory request amounts.	High wait times indicate too many queries are running concurrently that require query memory. Operations requiring query memory are hashes and sorts. Use DMVs such as dm_exec_query_resource_semaphores and dm_exec_query_memory_grants
RESOURCE_SEMAPHORE_QUERY_COMPILE	Compilation	>= 2005	Occurs when the number of concurrent query compilations reaches a throttling limit. High waits and wait times may indicate excessive compilations, recompiles, or uncachable plans.	This is a very complicated problem to explain. The problem is more than just concurrent compilations. It is the amount of memory required by the compilations. Typically this problem is not seen on 64bit systems. The biggest thing you can do is find out why you have so many compilations. Furthermore, a high amount of “query memory” can result in less memory available for compilations so check what other users are consuming high query memory.
SLEEP_BPOOL_FLUSH	Idle		Occurs when a checkpoint is throttling the issuance of new I/Os in order to avoid flooding the disk subsystem.
SLEEP_BUFFERPOOL_HELPLW	Idle
SLEEP_DBSTARTUP	Idle		Occurs during database startup while waiting for all databases to recover.
SLEEP_DCOMSTARTUP	Idle		Occurs once at most during SQL Server instance startup while waiting for DCOM initialization to complete.
SLEEP_MASTERDBREADY	Idle
SLEEP_MASTERMDREADY	Idle
SLEEP_MASTERUPGRADED	Idle
SLEEP_MEMORYPOOL_ALLOCATEPAGES	Idle
SLEEP_MSDBSTARTUP	Idle		Occurs when SQL Trace waits for the msdb database to complete startup.
SLEEP_RETRY_VIRTUALALLOC	Idle
SLEEP_SYSTEMTASK	Idle		Occurs during the start of a background task while waiting for tempdb to complete startup.
SLEEP_TASK	Idle		Occurs when a task sleeps while waiting for a generic event to occur.
SLEEP_TEMPDBSTARTUP	Idle		Occurs while a task waits for tempdb to complete startup.
SLEEP_WORKSPACE_ALLOCATEPAGE	Idle
SOS_SCHEDULER_YIELD	CPU	>= 2005	Occurs when a task voluntarily yields the scheduler for other tasks to execute. During this wait the task is waiting for its quantum to be renewed.	This wait is simply an indication that a worker yielded for someone else to run. High wait counts with low wait times usually mean CPU bound queries. High wait times here could be non-yielding problems
SQLCLR_APPDOMAIN	SQL CLR		Occurs while CLR waits for an application domain to complete startup.
SQLCLR_ASSEMBLY	SQL CLR		Occurs while waiting for access to the loaded assembly list in the appdomain.
SQLCLR_DEADLOCK_DETECTION	SQL CLR		Occurs while CLR waits for deadlock detection to complete.
SQLCLR_QUANTUM_PUNISHMENT	SQL CLR		Occurs when a CLR task is throttled because it has exceeded its execution quantum. This throttling is done in order to reduce the effect of this resource-intensive task on other tasks.
SQLTRACE_BUFFER_FLUSH	Idle	>= 2005	Occurs when a task is waiting for a background task to flush trace buffers to disk every four seconds.	You should be able to safely ignore unless some unexplained problem with SQLTrace files not getting written to disk properly.
SQLTRACE_FILE_BUFFER	Tracing		Occurs during synchronization on trace buffers during a file trace.
SQLTRACE_FILE_READ_IO_COMPLETION	Tracing
SQLTRACE_FILE_WRITE_IO_COMPLETION	Tracing
SQLTRACE_INCREMENTAL_FLUSH_SLEEP	Idle
SQLTRACE_PENDING_BUFFER_WRITERS	Tracing
SQLTRACE_SHUTDOWN	Tracing		Occurs while trace shutdown waits for outstanding trace events to complete.
SQLTRACE_WAIT_ENTRIES	Idle		Occurs while a SQL Trace event queue waits for packets to arrive on the queue.
THREADPOOL	Worker Thread	>= 2005	Occurs when a task is waiting for a worker to run on. This can indicate that the maximum worker setting is too low, or that batch executions are taking unusually long, thus reducing the number of workers available to satisfy other batches.	Look for symptoms of high blocking or contention problems with many of the workers especially if the wait count and times are high. Don’t jump to increase max worker threads especially if you use default setting of 0. This wait type will not show up in sys.dm_exec_requests because it only occurs when the task is waiting on a worker thread. You must have a worker to become a request. Furthermore, you may not see this “live” since there may be no workers to process tasks for logins or for queries to look at DMVs.
TRACE_EVTNOTIF	Tracing
TRACEWRITE	Tracing		Occurs when the SQL Trace rowset trace provider waits for either a free buffer or a buffer with events to process.
TRAN_MARKLATCH_DT	Transaction		Occurs when waiting for a destroy mode latch on a transaction mark latch. Transaction mark latches are used for synchronization of commits with marked transactions.
TRAN_MARKLATCH_EX	Transaction		Occurs when waiting for an exclusive mode latch on a marked transaction. Transaction mark latches are used for synchronization of commits with marked transactions.
TRAN_MARKLATCH_KP	Transaction		Occurs when waiting for a keep mode latch on a marked transaction. Transaction mark latches are used for synchronization of commits with marked transactions.
TRAN_MARKLATCH_NL	Transaction		Identified for informational purposes only. Not supported. Future compatibility is not guaranteed.
TRAN_MARKLATCH_SH	Transaction		Occurs when waiting for a shared mode latch on a marked transaction. Transaction mark latches are used for synchronization of commits with marked transactions.
TRAN_MARKLATCH_UP	Transaction		Occurs when waiting for an update mode latch on a marked transaction. Transaction mark latches are used for synchronization of commits with marked transactions.
TRANSACTION_MUTEX	Transaction		Occurs during synchronization of access to a transaction by multiple batches.
WAIT_FOR_RESULTS	User Wait		Occurs when waiting for a query notification to be triggered.
WAITFOR	User Wait		Occurs as a result of a WAITFOR Transact-SQL statement. The duration of the wait is determined by the parameters to the statement. This is a user-initiated wait.
WRITE_COMPLETION	Other Disk IO		Occurs when a write operation is in progress.
WRITELOG	Tran Log IO	>= 2005	Occurs while waiting for a log flush to complete. Common operations that cause log flushes are checkpoints and transaction commits.	High waits and wait times indicate an I/O bottleneck on the storage system associated with the transaction log
XACT_OWN_TRANSACTION	Transaction		Occurs while waiting to acquire ownership of a transaction.
XACT_RECLAIM_SESSION	Transaction		Occurs while waiting for the current owner of a session to release ownership of the session.
XACTLOCKINFO	Transaction		Occurs during synchronization of access to the list of locks for a transaction. In addition to the transaction itself, the list of locks is accessed by operations such as deadlock detection and lock migration during page splits.
XACTWORKSPACE_MUTEX	Transaction		Occurs during synchronization of defections from a transaction, as well as the number of database locks between enlist members of a transaction.
XE_DISPATCHER_WAIT	Idle	>= 2008	Occurs when a background thread that is used for Extended Events sessions is waiting for event buffers to process.	You should be able to safely ignore this unless you believe a problem is occurring with processing of events for async targets. Since this works on a queue you can have bursts of high wait times especially when no XEvent sessions are active.
XE_TIMER_EVENT	Idle	>= 2008	Used to indicate a background task is waiting for “expired” timers for internal Xevent engine work	You should be able to safely ignore this one. Just used by the Xevent engine for internal processing of its work. If something was possibly wrong with Xevent processing you might see if this thread ever “wakes up”

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