The SQL Operators event classes can be used to monitor when a DELETE, INSERT, SELECT, or UPDATE query occurs.
| Event class | Description |
|---|---|
| Delete | Occurs before a DELETE statement is executed. |
| Insert | Occurs before an INSERT statement is executed. |
| Select | Occurs before a SELECT statement is executed. |
| Update | Occurs before an UPDATE statement is executed. |
The Event Sub Class data column for each operator can be used for monitoring if the query optimizer generates a parallel query execution plan for the specific SQL operator.
| Event class | Data column | Description |
|---|---|---|
| Delete | Event Sub Class | Degree of parallelism (number of CPUs used to perform the DELETE). |
| Insert | Event Sub Class | Degree of parallelism (number of CPUs used to perform the INSERT). |
| Select | Event Sub Class | Degree of parallelism (number of CPUs used to perform the SELECT). |
| Update | Event Sub Class | Degree of parallelism (number of CPUs used to perform the UPDATE). |
The degree of parallelism chosen for each query plan execution is defined as follows:
| Event Sub Class value |
Description |
|---|---|
| 0 | No parallelism considered because Microsoft® SQL Server™ could execute the query only on a single CPU. This occurs when: The computer has only one processor. The max degree of parallelism server configuration option is set to 1. For more information, see max degree of parallelism Option. The MAXDOP 1 query hint is specified. For more information, see SELECT. The Desktop version of SQL Server is being used. |
| 1 | Parallel execution considered, but the query is executed using a serial plan because either the query is trivial, the cost of executing the query is less than the cost threshold for parallelism value, or there are not enough resources available to execute a parallel plan. For more information, see cost threshold for parallelism Option. |
| >1 | For a DELETE, INSERT, SELECT, or UPDATE statement, the whole or a portion of the query is executed using a parallel execution plan with the shown degree of parallelism. |
To achieve proper and efficient parallel query execution, setting configuration parameters is not required.
Every parallel plan contains either the Distribute Streams, Gather Streams, or Repartition Streams logical operators. For more information, see Logical and Physical Operators.
Note Although system administrators can influence the query optimizer’s generation of parallel query execution plans by changing the values for the cost threshold for parallelism and max degree of parallelism server configuration options using the sp_configure system stored procedure, it is not recommended. For more information, see Setting Configuration Options.