Holds information about all requests currently or recently active in PolyBase queries. It lists one row per request/query.
Based on session and request ID, a user can then retrieve the actual distributed requests generated to be executed - via sys.dm_exec_distributed_requests. For example, a query involving regular SQL and external SQL tables will be decomposed into various statements/requests executed across the various compute nodes. To track the distributed steps across all compute nodes, we introduce a 'global' execution ID which can be used to track all operations on the compute nodes associated with one particular request and operator, respectively.
|Column Name||Data Type||Description||Range|
|sql_handle||varbinary(64)||Key for this view. Unique numeric id associated with the request.||Unique across all requests in the system.|
|execution_id||nvarchar(32||Unique numeric id associated with the session in which this query was run.|
|status||nvarchar(32||Current status of the request.||'Pending', 'Authorizing', 'AcquireSystemResources', 'Initializing', 'Plan', 'Parsing', 'AquireResources', 'Running', 'Cancelling', 'Complete', 'Failed', 'Cancelled'.|
|error_id||nvarchar(36)||Unique id of the error associated with the request, if any.||Set to NULL if no error occurred.|
|start_time||datetime||Time at which the request execution was started.||0 for queued requests; otherwise, valid datetime smaller or equal to current time.|
|end_time||datetime||Time at which the engine completed compiling the request.||Null for queued or active requests; otherwise, a valid datetime smaller or equal to current time.|
|total_elapsed_time||int||Time elapsed in execution since the request was started, in milliseconds.||Between 0 and the difference between start_time and end_time.If total_elapsed_time exceeds the maximum value for an integer, total_elapsed_time will continue to be the maximum value. This condition will generate the warning "The maximum value has been exceeded." The maximum value in milliseconds is equivalent to 24.8 days.|