sys.dm_exec_requests (Transact-SQL)
Applies to:
SQL Server
Azure SQL Database
Azure SQL Managed Instance
Azure Synapse Analytics
Analytics Platform System (PDW)
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.
Permissions for SQL Server 2022 and later
Requires VIEW SERVER PERFORMANCE STATE permission on the server.
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
- Dynamic Management Views and Functions
- Execution Related Dynamic Management Views and Functions
- sys.dm_os_memory_clerks
- sys.dm_os_sys_info
- sys.dm_exec_query_memory_grants
- sys.dm_exec_query_plan
- sys.dm_exec_sql_text
- SQL Server, SQL Statistics Object
- Query Processing Architecture Guide
- Thread and Task Architecture Guide