Description This wait type is only used for databases participating in an Availability Group. When multiple log records can be batched together SQL Server can optimize distribution to replicas by performing a group commit. When SQL Server is waiting for the group commit to complete this wait will accumulate. As this wait type accumulates during […]

Description Occurs when Availability Group databases version state changes. This refers to row versioning, example read committed snapshot. Resolved by DBAs Suggested solutions Small values are ignorable. However, if the values are large check the SQL Server error log for more information Ensure performance of volumes holding replica data and logs files is adequate Additional […]

Description This wait type is only used for databases participating in an Availability Group. When an instance reaches certain thresholds (additional research links below) SQL Server will accumulate this wait as well as restrict activity by enabling Availability Flow Control. This mechanism prevents the Secondary Replicas from becoming overwhelmed. Flow control is based on the […]

Description This wait occurs on databases with snapshots. When the primary database is updated the original page must be written to any snapshots, during writes to the snapshot sparse file this wait will accumulate. The wait will also accumulate during DBCC CHECKDB operations as a snapshot is temporarily created internally Resolved by DBAs Suggested solutions […]

Description This wait occurs on databases with snapshots. When the primary database is updated the original page must be written to any snapshots, during reads to the snapshot sparse file this wait will accumulate. The wait will also accumulate during DBCC CHECKDB operations as a snapshot is temporarily created internally Resolved by DBAs Suggested solutions […]

Description Accumulates during certain Distributed Transaction Co-Ordinator (DTC) operations. This wait is rare and currently not documented by Microsoft. If values are excessive see the suggested solutions below Resolved by DBAs Suggested solutions Check the error logs on every instance the transaction is running on Keep distributed transactions as short as possible Ensure that Linked […]

Description This wait type accumulates while SQL Server is waiting for the Distributed Transaction Co-Ordinator (DTC) to receive the outcome of a transaction. Distributed transactions run across multiple database instances and sometimes other platforms like Oracle. This wait type is uncommon and if values are excessive then further investigation is required Resolved by DBAs Suggested […]

Description This wait type accumulates while SQL Server is waiting for the Distributed Transaction Co-Ordinator (DTC) to access the internal service global state object. Distributed transactions run across multiple database instances and sometimes other platforms like Oracle. This wait type is uncommon and if values are excessive then further investigation is required Resolved by DBAs […]

Description This wait type accumulates while SQL Server is waiting for the Distributed Transaction Co-Ordinator (DTC) to resolve a transaction. Transaction resolution is performed by the transaction’s master database. Distributed transactions run across multiple database instances and sometimes other platforms like Oracle. This wait type is uncommon and if values are excessive then further investigation […]

Description This wait type accumulates while SQL Server is waiting for the Distributed Transaction Co-Ordinator (DTC) to cancel a transaction. Distributed transactions run across multiple database instances and sometimes other platforms like Oracle. If this wait type is high further investigation is required Resolved by DBAs Suggested solutions Check the error logs on every instance […]

Description This wait type accumulates while running requests through the Distributed Transaction Co-Ordinator (DTC). Distributed transactions run across multiple database instances and sometimes other platforms like Oracle. If this wait type is high it indicates these transactions could be a bottleneck Resolved by DBAs and Developers Suggested solutions Keep distributed transactions as short as possible […]

Description For databases using mirroring. This wait type accumulates while SQL Server is waiting for transaction log records to be flushed to disk. High values are expected but if this is experienced along side extended mirror latencies then investigation is required. Please note that database mirroring is a deprecated feature and could be removed in […]

Description For databases using mirroring. This wait type accumulates while mirroring is waiting to receive work. As this is an idling wait high values are expected and do not indicate an issue. Please note that database mirroring is a deprecated feature and could be removed in an upcoming release. Investigation into other high availability and […]

Description For databases using mirroring. This wait type accumulates while messages and transaction log records are waiting for the communication layer to become available. Some values in this wait are expected but high values indicate a bottleneck. Please note that database mirroring is a deprecated feature and could be removed in an upcoming release. Investigation […]

Description For databases using mirroring. This wait type accumulates during mirroring activity. It is used internally so it is not formally documented by Microsoft. Moderate values tend to not be problematic but if high values are experienced then investigating other mirroring waits are recommended. Please note that database mirroring is a deprecated feature and could […]

Description For databases using mirroring. This wait type accumulates during mirroring activity. It is used internally so it is not formally documented by Microsoft. As this wait is uncommon low values tend to not be problematic. If moderate values are experienced then investigating other mirroring waits is recommended. Please note that database mirroring is a […]

Description This wait type accumulates while a transaction commit is being performed on a table with Change Tracking enabled. This wait type is not documented by Microsoft so not much is known about it. If values are excessive then investigation is required Resolved by DBAs Suggested solutions Only enable Change Tracking on tables and columns […]

Description This wait type accumulates during certain operations on databases with Change Tracking enabled. This wait type is not documented by Microsoft so not much is known about it. This wait type is uncommon and should be investigated if any values exist Resolved by DBAs Suggested solutions Only enable Change Tracking on tables and columns […]

Description This wait type accumulates while SQL Server is waiting for thread-safe memory object. The most common memory object effected is the plan cache, especially when plans are rapidly added or removed from the cache. This wait is common and moderate values do not indicate major issue. If values are excessive investigation is required Resolved […]

Description This wait accumulates during execution of CLR (Common Language Runtime). As this is an idling wait it is safe to ignore Resolved by DBAs Suggested solutions This wait is safe to ignore. However, if CLR code is experiencing performance issues please investigate other counters as per the additional research links below Additional research CLR_AUTO_EVENT […]

Description For databases using Service Broker. This wait accumulates while Service Broker is waiting to receive work. As this is an idle wait high values are expected and indicate normal activity Resolved by DBAs Suggested solutions Safe to ignore Additional research Service Broker: Performance and Scalability Techniques How to troubleshoot Service Broker problems ⇐ Back […]

Description For databases using Service Broker. This wait accumulates while Service Broker is processing messages for transmission. This wait was introduced in SQL Server 2012, is common and currently is not documented by Microsoft. High values indicate normal activity Resolved by DBAs Suggested solutions If values are excessively high, ensure Service Broker objects are designed […]

Description For databases using Service Broker. This wait accumulates while Service Broker is sending and receiving data through tables. This wait was introduced in SQL Server 2012, is common and currently is not documented by Microsoft. High values indicate normal activity Resolved by DBAs Suggested solutions If values are excessively high, ensure Service Broker objects […]

Description For databases using Service Broker. This wait accumulates while Service Broker is sending and receiving objects. This wait was introduced in SQL Server 2012, is uncommon and currently is not documented by Microsoft. High values indicate normal activity Resolved by DBAs Suggested solutions If values are excessively high, ensure Service Broker objects are designed […]

Description For databases using Service Broker. This wait accumulates while a Service Broker queue is waiting to submit a task into a queue. This wait is uncommon and any values should be investigated Resolved by DBAs Suggested solutions Check the SQL Server error log for any Service Broker issues Ensure Service Broker objects are designed […]