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sys.dm_os_performance_counters (Transact-SQL)

  • Straipsnis

Applies to: SQL Server Azure SQL Database Azure SQL Managed Instance Azure Synapse Analytics Analytics Platform System (PDW)

Returns a row per performance counter maintained by the server. For information about each performance counter, see Use SQL Server Objects.

Note

To call this from Azure Synapse Analytics or Analytics Platform System (PDW), use the name sys.dm_pdw_nodes_os_performance_counters. This syntax is not supported by serverless SQL pool in Azure Synapse Analytics.

Column name Data type Description
object_name nchar(128) Category to which this counter belongs.
counter_name nchar(128) Name of the counter. To get more information about a counter, this is the name of the topic to select from the list of counters in Use SQL Server Objects.
instance_name nchar(128) Name of the specific instance of the counter. Often contains the database name.
cntr_value bigint Current value of the counter.

Note: For per-second counters, this value is cumulative. The rate value must be calculated by sampling the value at discrete time intervals. The difference between any two successive sample values is equal to the rate for the time interval used.
cntr_type int Type of counter as defined by the Windows performance architecture. See WMI Performance Counter Types on Docs or your Windows Server documentation for more information on performance counter types.
pdw_node_id int Applies to: Azure Synapse Analytics, Analytics Platform System (PDW)

The identifier for the node that this distribution is on.

Remarks

If the installation instance of SQL Server fails to display the performance counters of the Windows operating system, use the following Transact-SQL query to confirm that performance counters have been disabled.

SELECT COUNT(*) FROM sys.dm_os_performance_counters;

If the return value is 0 rows, this means that the performance counters have been disabled. You should then look at the setup log and search for error 3409, Reinstall sqlctr.ini for this instance, and ensure that the instance login account has correct registry permissions. This denotes that performance counters were not enabled. The errors immediately before the 3409 error should indicate the root cause for the failure of performance counter enabling. For more information about setup log files, see View and Read SQL Server Setup Log Files.

Performance counters where the cntr_type column value is 65792 display a snapshot of the last observed value only, not an average.

Performance counters where the cntr_type column value is 272696320 or 272696576 display the average number of operations completed during each second of the sample interval. Counters of this type measure time in ticks of the system clock. For example, to get a snapshot-like reading of the last second only for the Buffer Manager:Lazy writes/sec and Buffer Manager:Checkpoint pages/sec counters, you must compare the delta between two collection points that are one second apart.

Performance counters where the cntr_type column value is 537003264 display the ratio of a subset to its set as a percentage. For example, the Buffer Manager:Buffer cache hit ratio counter compares the total number of cache hits and the total number of cache lookups. As such, to get a snapshot-like reading of the last second only, you must compare the delta between the current value and the base value (denominator) between two collection points that are one second apart. The corresponding base value is the performance counter Buffer Manager:Buffer cache hit ratio base where the cntr_type column value is 1073939712.

Performance counters where the cntr_type column value is 1073874176 display how many items are processed on average, as a ratio of the items processed to the number of operations. For example, the Locks:Average Wait Time (ms) counters compares the lock waits per second with the lock requests per second, to display the average amount of wait time (in milliseconds) for each lock request that resulted in a wait. As such, to get a snapshot-like reading of the last second only, you must compare the delta between the current value and the base value (denominator) between two collection points that are one second apart. The corresponding base value is the performance counter Locks:Average Wait Time Base where the cntr_type column value is 1073939712.

Data in the sys.dm_os_performance_counters DMV is not persisted after the database engine restarts. Use the sqlserver_start_time column in sys.dm_os_sys_info to find the last database engine startup time.

Permission

On SQL Server and SQL Managed Instance, requires VIEW SERVER STATE permission.

On SQL Database Basic, S0, and S1 service objectives, and for databases in elastic pools, the server admin account, the Microsoft Entra admin account, or membership in the ##MS_ServerStateReader## server role is required. On all other SQL Database service objectives, either the VIEW DATABASE STATE permission on the database, or membership in the ##MS_ServerStateReader## server role is required.

Permissions for SQL Server 2022 and later

Requires VIEW SERVER PERFORMANCE STATE permission on the server.

Examples

The following example returns all performance counters that display snapshot counter values.

SELECT object_name, counter_name, instance_name, cntr_value, cntr_type  
FROM sys.dm_os_performance_counters
WHERE cntr_type = 65792 OR cntr_type = 272696320 OR cntr_type = 537003264;

See also

SQL Server Operating System Related Dynamic Management Views (Transact-SQL)
sys.sysperfinfo (Transact-SQL)
sys.dm_os_sys_info (Transact-SQL)