SQL Wait Types Test
In SQL Server, wait types represent the discrete steps in query processing, where a query waits for resources as the instance completes the request. By analysing wait types and their wait times, administrators can receive quick and objective evidence of performance bottlenecks and their probable causes. The SQL Wait Types test enables this analysis. For every type of wait that is currently experienced by the server, this test reports the number, nature, and duration of waits, thereby leading you to the specific wait types that may have contributed to a general slowdown/deterioration in server performance.
Target of the test : A Microsoft SQL server
Agent deploying the test : An internal agent
Outputs of the test : One set of results for every type of wait in the Microsoft SQL server monitored
|
Measurement | Description | Measurement Unit | Interpretation |
---|---|---|---|
Waiting tasks count: |
Indicates the number of waits of this type during the last measurement period. |
Number |
This counter is incremented at the start of each wait. |
Tasks avg wait time: |
Indicates the total wait time for this wait type during the last measurement period. |
MilliSecs |
A low value is desired for this measure. When a user complaints that query execution takes too long, you can compare the value of this measure across wait types to know which type of wait is the key contributor to delays in query processing. |
Tasks avg signal wait time: |
Indicates the total signal wait time for this wait type during the last measurement period. |
MilliSecs |
The signal wait is the time between when a worker has been granted access to the resource and the time it gets scheduled on the CPU. A high value for this measure may imply a high CPU contention. To know which wait type registered the highest signal wait time and probably caused the CPU contention, compare the value of this measure across wait types. |
Tasks avg resource wait time: |
Indicates the total resource wait time for this wait type during the last measurement period. |
MilliSecs |
Resource wait time is the actual time a worker waited for the resource to be available. A high value for this measure indicates a delay in acquiring a resource. To know which wait type waited the longest for a resource and therefore contributed to a server slowdown, compare the value of this measure across wait types. |
Tasks wait time: |
Indicates the percentage of total wait time (across wait types) during which wait events of this type occurred. |
Percent |
When a user complaints that query execution takes too long, you can compare the value of this measure across wait types to know which type of wait is the key contributor to delays in query processing. |
Tasks signal wait time: |
Indicates the percentage of total signal wait time (across wait types) during which wait events of this type waited for a signal. |
Percent |
The signal wait is the time between when a worker has been granted access to the resource and the time it gets scheduled on the CPU. A high value for this measure may imply a high CPU contention. To know which wait type registered the highest signal wait time and probably caused the CPU contention, compare the value of this measure across wait types. |
Tasks resource wait time: |
Indicates the percentage of total resource wait time (across wait types) during which wait events of this type waited for a resource. |
Percent |
Resource wait time is the actual time a worker waited for the resource to be available. A high value for this measure indicates a delay in acquiring a resource. To know which wait type waited the longest for a resource and therefore contributed to a server slowdown, compare the value of this measure across wait types. |