CXPACKET waits occur when a parallel query is executed and one or more threads have to wait on one of the other threads to complete. SQL Server parallelizes a query by dividing each query operation into equal sized sets and by splitting up these sets into multiple threads targeting specific processors for parallel processing. Because not all the threads complete at exactly the same time, the server experiences CXPACKET waits.
Parallel queries require extra overhead to coordinate the parallel processing along with the initialization, synchronization, and termination of the parallel plan. If you have a parallel query execution , you will have CXPACKET waits. |
CXPACKET waits are of concern only if they are in excess. High CXPACKET waits indicate that some performance tuning is necessary on a specific query or the whole SQL Server.
The causes for experiencing high CXPACKET in your SQL Server can be any of the following:
If you experience high CXPACKET waits in your OLTP server, it is generally due to one or more of the following:
Use the following process to keep regular maintenance of your index and statistics and to control CXPACKET waits:
You can review the query plans from the plan cache to identify queries that can be parallelized. Use the following links to find scripts for viewing your query plans:
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