sys.dm_exec_requests (Transact-SQL)

Applies to: yesSQL Server (all supported versions) YesAzure SQL Database yesAzure Synapse Analytics

Returns information about each request that is executing in SQL Server. For more information about requests, see the Thread and Task Architecture Guide.

Note

To call this from dedicated SQL pool in Azure Synapse Analytics or Analytics Platform System (PDW), see sys.dm_pdw_exec_requests (Transact-SQL). For serverless SQL pool use sys.dm_exec_requests.

Column name Data type Description
session_id smallint ID of the session to which this request is related. Isn't nullable.
request_id int ID of the request. Unique in the context of the session. Isn't nullable.
start_time datetime Timestamp when the request arrived. Isn't nullable.
status nvarchar(30) Status of the request. Can be one of the following values:

Background
Running
Runnable
Sleeping
Suspended

Isn't nullable.
command nvarchar(32) Identifies the current type of command that is being processed. Common command types include the following values:

SELECT
INSERT
UPDATE
DELETE
BACKUP LOG
BACKUP DATABASE
DBCC
FOR

The text of the request can be retrieved by using sys.dm_exec_sql_text with the corresponding sql_handle for the request. Internal system processes set the command based on the type of task they perform. Tasks can include the following values:

LOCK MONITOR
CHECKPOINTLAZY
WRITER

Isn't nullable.
sql_handle varbinary(64) Is a token that uniquely identifies the batch or stored procedure that the query is part of. Is nullable.
statement_start_offset int Indicates, in bytes, beginning with 0, the starting position of the currently executing statement for the currently executing batch or persisted object. Can be used together with the sql_handle, the statement_end_offset, and the sys.dm_exec_sql_text dynamic management function to retrieve the currently executing statement for the request. Is nullable.
statement_end_offset int Indicates, in bytes, starting with 0, the ending position of the currently executing statement for the currently executing batch or persisted object. Can be used together with the sql_handle, the statement_start_offset, and the sys.dm_exec_sql_text dynamic management function to retrieve the currently executing statement for the request. Is nullable.
plan_handle varbinary(64) Is a token that uniquely identifies a query execution plan for a batch that is currently executing. Is nullable.
database_id smallint ID of the database the request is executing against. Isn't nullable.
user_id int ID of the user who submitted the request. Isn't nullable.
connection_id uniqueidentifier ID of the connection on which the request arrived. Is nullable.
blocking_session_id smallint ID of the session that is blocking the request. If this column is NULL or equal to 0, the request isn't blocked, or the session information of the blocking session isn't available (or can't be identified). For more information, see Understand and resolve SQL Server blocking problems.

-2 = The blocking resource is owned by an orphaned distributed transaction.

-3 = The blocking resource is owned by a deferred recovery transaction.

-4 = Session ID of the blocking latch owner couldn't be determined at this time because of internal latch state transitions.

-5 = Session ID of the blocking latch owner couldn't be determined because it isn't tracked for this latch type (for example, for an SH latch).

By itself, blocking_session_id -5 doesn't indicate a performance problem. -5 is an indication that the session is waiting on an asynchronous action to complete. Before -5 was introduced, the same session would have shown blocking_session_id 0, even though it was still in a wait state.

Depending on workload, observing -5 as blocking_session_id may be a common occurrence.
wait_type nvarchar(60) If the request is currently blocked, this column returns the type of wait. Is nullable.

For information about types of waits, see sys.dm_os_wait_stats (Transact-SQL).
wait_time int If the request is currently blocked, this column returns the duration in milliseconds, of the current wait. Isn't nullable.
last_wait_type nvarchar(60) If this request has previously been blocked, this column returns the type of the last wait. Isn't nullable.
wait_resource nvarchar(256) If the request is currently blocked, this column returns the resource for which the request is currently waiting. Isn't nullable.
open_transaction_count int Number of transactions that are open for this request. Isn't nullable.
open_resultset_count int Number of result sets that are open for this request. Isn't nullable.
transaction_id bigint ID of the transaction in which this request executes. Isn't nullable.
context_info varbinary(128) CONTEXT_INFO value of the session. Is nullable.
percent_complete real Percentage of work completed for the following commands:

ALTER INDEX REORGANIZE
AUTO_SHRINK option with ALTER DATABASE
BACKUP DATABASE
DBCC CHECKDB
DBCC CHECKFILEGROUP
DBCC CHECKTABLE
DBCC INDEXDEFRAG
DBCC SHRINKDATABASE
DBCC SHRINKFILE
RECOVERY
RESTORE DATABASE
ROLLBACK
TDE ENCRYPTION

Isn't nullable.
estimated_completion_time bigint Internal only. Isn't nullable.
cpu_time int CPU time in milliseconds that is used by the request. Isn't nullable.
total_elapsed_time int Total time elapsed in milliseconds since the request arrived. Isn't nullable.
scheduler_id int ID of the scheduler that is scheduling this request. Is nullable.
task_address varbinary(8) Memory address allocated to the task that is associated with this request. Is nullable.
reads bigint Number of reads performed by this request. Isn't nullable.
writes bigint Number of writes performed by this request. Isn't nullable.
logical_reads bigint Number of logical reads that have been performed by the request. Isn't nullable.
text_size int TEXTSIZE setting for this request. Isn't nullable.
language nvarchar(128) Language setting for the request. Is nullable.
date_format nvarchar(3) DATEFORMAT setting for the request. Is nullable.
date_first smallint DATEFIRST setting for the request. Isn't nullable.
quoted_identifier bit 1 = QUOTED_IDENTIFIER is ON for the request. Otherwise, it's 0.

isn't nullable.
arithabort bit 1 = ARITHABORT setting is ON for the request. Otherwise, it's 0.

isn't nullable.
ansi_null_dflt_on bit 1 = ANSI_NULL_DFLT_ON setting is ON for the request. Otherwise, it's 0.

isn't nullable.
ansi_defaults bit 1 = ANSI_DEFAULTS setting is ON for the request. Otherwise, it's 0.

isn't nullable.
ansi_warnings bit 1 = ANSI_WARNINGS setting is ON for the request. Otherwise, it's 0.

Isn't nullable.
ansi_padding bit 1 = ANSI_PADDING setting is ON for the request.

Otherwise, it's 0.

isn't nullable.
ansi_nulls bit 1 = ANSI_NULLS setting is ON for the request. Otherwise, it's 0.

isn't nullable.
concat_null_yields_null bit 1 = CONCAT_NULL_YIELDS_NULL setting is ON for the request. Otherwise, it's 0.

isn't nullable.
transaction_isolation_level smallint Isolation level with which the transaction for this request is created. isn't nullable.
0 = Unspecified
1 = ReadUncomitted
2 = ReadCommitted
3 = Repeatable
4 = Serializable
5 = Snapshot
lock_timeout int Lock time-out period in milliseconds for this request. isn't nullable.
deadlock_priority int DEADLOCK_PRIORITY setting for the request. isn't nullable.
row_count bigint Number of rows that have been returned to the client by this request. isn't nullable.
prev_error int Last error that occurred during the execution of the request. isn't nullable.
nest_level int Current nesting level of code that is executing on the request. isn't nullable.
granted_query_memory int Number of pages allocated to the execution of a query on the request. isn't nullable.
executing_managed_code bit Indicates whether a specific request is currently executing common language runtime objects, such as routines, types, and triggers. it's set for the full time a common language runtime object is on the stack, even while running Transact-SQL from within common language runtime. isn't nullable.
group_id int ID of the workload group to which this query belongs. isn't nullable.
query_hash binary(8) Binary hash value calculated on the query and used to identify queries with similar logic. You can use the query hash to determine the aggregate resource usage for queries that differ only by literal values.
query_plan_hash binary(8) Binary hash value calculated on the query execution plan and used to identify similar query execution plans. You can use query plan hash to find the cumulative cost of queries with similar execution plans.
statement_sql_handle varbinary(64) Applies to: SQL Server 2014 (12.x) and later.

SQL handle of the individual query.

This column is NULL if Query Store isn't enabled for the database.
statement_context_id bigint Applies to: SQL Server 2014 (12.x) and later.

The optional foreign key to sys.query_context_settings.

This column is NULL if Query Store isn't enabled for the database.
dop int Applies to: SQL Server 2016 (13.x) and later.

The degree of parallelism of the query.
parallel_worker_count int Applies to: SQL Server 2016 (13.x) and later.

The number of reserved parallel workers if this is a parallel query.
external_script_request_id uniqueidentifier Applies to: SQL Server 2016 (13.x) and later.

The external script request ID associated with the current request.
is_resumable bit Applies to: SQL Server 2017 (14.x) and later.

Indicates whether the request is a resumable index operation.
page_resource binary(8) Applies to: SQL Server 2019 (15.x)

An 8-byte hexadecimal representation of the page resource if the wait_resource column contains a page. For more information, see sys.fn_PageResCracker.
page_server_reads bigint Applies to: Azure SQL Database Hyperscale

Number of page server reads performed by this request. isn't nullable.
     

Remarks

To execute code that is outside SQL Server (for example, extended stored procedures and distributed queries), a thread has to execute outside the control of the non-preemptive scheduler. To do this, a worker switches to preemptive mode. Time values returned by this dynamic management view don't include time spent in preemptive mode.

When executing parallel requests in row mode, SQL Server assigns a worker thread to coordinate the worker threads responsible for completing tasks assigned to them. In this DMV, only the coordinator thread is visible for the request. The columns reads, writes, logical_reads, and row_count are not updated for the coordinator thread. The columns wait_type, wait_time, last_wait_type, wait_resource, and granted_query_memory are only updated for the coordinator thread. For more information, see the Thread and Task Architecture Guide.

Permissions

If the user has VIEW SERVER STATE permission on the server, the user will see all executing sessions on the instance of SQL Server; otherwise, the user will see only the current session. VIEW SERVER STATE can't be granted in Azure SQL Database so sys.dm_exec_requests is always limited to the current connection.

In Always-On scenarios, if the secondary replica is set to read-intent only, the connection to the secondary must specify its application intent in connection string parameters by adding applicationintent=readonly. Otherwise, the access check for sys.dm_exec_requests won't pass for databases in the availability group, even if VIEW SERVER STATE permission is present.

Examples

A. Finding the query text for a running batch

The following example queries sys.dm_exec_requests to find the interesting query and copy its sql_handle from the output.

SELECT * FROM sys.dm_exec_requests;  
GO  

Then, to obtain the statement text, use the copied sql_handle with system function sys.dm_exec_sql_text(sql_handle).

SELECT * FROM sys.dm_exec_sql_text(< copied sql_handle >);  
GO  

B. Finding all locks that a running batch is holding

The following example queries sys.dm_exec_requests to find the interesting batch and copy its transaction_id from the output.

SELECT * FROM sys.dm_exec_requests;  
GO

Then, to find lock information, use the copied transaction_id with the system function sys.dm_tran_locks.

SELECT * FROM sys.dm_tran_locks
WHERE request_owner_type = N'TRANSACTION'
    AND request_owner_id = < copied transaction_id >;
GO  

C. Finding all currently blocked requests

The following example queries sys.dm_exec_requests to find information about blocked requests.

SELECT session_id, status, blocking_session_id  
    , wait_type, wait_time, wait_resource
    , transaction_id
FROM sys.dm_exec_requests
WHERE status = N'suspended';  
GO  

D. Ordering existing requests by CPU

SELECT 
   req.session_id
   , req.start_time
   , cpu_time 'cpu_time_ms'
   , object_name(st.objectid,st.dbid) 'ObjectName' 
   , substring
      (REPLACE
        (REPLACE
          (SUBSTRING
            (ST.text
            , (req.statement_start_offset/2) + 1
            , (
               (CASE statement_end_offset
                  WHEN -1
                  THEN DATALENGTH(ST.text)  
                  ELSE req.statement_end_offset
                  END
                    - req.statement_start_offset)/2) + 1)
       , CHAR(10), ' '), CHAR(13), ' '), 1, 512)  AS statement_text  
FROM sys.dm_exec_requests AS req  
   CROSS APPLY sys.dm_exec_sql_text(req.sql_handle) as ST
   ORDER BY cpu_time desc;
GO

See also

Next steps