# SQL Server Input Plugin

The `sqlserver` plugin provides metrics for your SQL Server instance.
Recorded metrics are lightweight and use Dynamic Management Views
supplied by SQL Server.

## The SQL Server plugin supports the following editions/versions of SQL Server

- SQL Server
  - 2012 or newer (Plugin support aligned with the [official Microsoft SQL Server support](https://docs.microsoft.com/en-us/sql/sql-server/end-of-support/sql-server-end-of-life-overview?view=sql-server-ver15#lifecycle-dates))
  - End-of-life SQL Server versions are not guaranteed to be supported by Telegraf. Any issues with the SQL Server plugin for these EOL versions will need to be addressed by the community.
- Azure SQL Database (Single)
- Azure SQL Managed Instance
- Azure SQL Elastic Pool
- Azure Arc-enabled SQL Managed Instance

## Additional Setup

You have to create a login on every SQL Server instance or Azure SQL
Managed instance you want to monitor, with following script:

```sql
USE master;
GO
CREATE LOGIN [telegraf] WITH PASSWORD = N'mystrongpassword';
GO
GRANT VIEW SERVER STATE TO [telegraf];
GO
GRANT VIEW ANY DEFINITION TO [telegraf];
GO
```

For Azure SQL Database, you require the View Database State permission
and can create a user with a password directly in the database.

```sql
CREATE USER [telegraf] WITH PASSWORD = N'mystrongpassword';
GO
GRANT VIEW DATABASE STATE TO [telegraf];
GO
```

For Azure SQL Elastic Pool, please follow the following instructions
to collect metrics.

On master logical database, create an SQL login 'telegraf' and assign
it to the server-level role ##MS_ServerStateReader##.

```sql
CREATE LOGIN [telegraf] WITH PASSWORD = N'mystrongpassword';
GO
ALTER SERVER ROLE ##MS_ServerStateReader##
  ADD MEMBER [telegraf];
GO
```

Elastic pool metrics can be collected from any database in the pool if a user
for the `telegraf` login is created in that database. For collection to work,
this database must remain in the pool, and must not be renamed. If you plan
to add/remove databases from this pool, create a separate database for
monitoring purposes that will remain in the pool.

> Note: To avoid duplicate monitoring data, do not collect elastic pool metrics
from more than one database in the same pool.

```sql
GO
CREATE USER [telegraf] FOR LOGIN telegraf;
```

For Service SID authentication to SQL Server (Windows service installations
only).

- [More information about using service SIDs to grant permissions in SQL Server](https://docs.microsoft.com/en-us/sql/relational-databases/security/using-service-sids-to-grant-permissions-to-services-in-sql-server)

In an administrative command prompt configure the telegraf service for use
with a service SID

```Batchfile
sc.exe sidtype "telegraf" unrestricted
```

To create the login for the telegraf service run the following script:

```sql
USE master;
GO
CREATE LOGIN [NT SERVICE\telegraf] FROM WINDOWS;
GO
GRANT VIEW SERVER STATE TO [NT SERVICE\telegraf];
GO
GRANT VIEW ANY DEFINITION TO [NT SERVICE\telegraf];
GO
```

Remove User Id and Password keywords from the connection string in your
config file to use windows authentication.

```toml
[[inputs.sqlserver]]
  servers = ["Server=192.168.1.10;Port=1433;app name=telegraf;log=1;",]
```

To set up a configurable timeout, add timeout to the connections string
in your config file.

```toml
servers = [
  "Server=192.168.1.10;Port=1433;User Id=<user>;Password=<pw>;app name=telegraf;log=1;dial timeout=30",
]
```

## Global configuration options <!-- @/docs/includes/plugin_config.md -->

In addition to the plugin-specific configuration settings, plugins support
additional global and plugin configuration settings. These settings are used to
modify metrics, tags, and field or create aliases and configure ordering, etc.
See the [CONFIGURATION.md][CONFIGURATION.md] for more details.

[CONFIGURATION.md]: ../../../docs/CONFIGURATION.md#plugins

## Secret-store support

This plugin supports secrets from secret-stores for the `servers` option.
See the [secret-store documentation][SECRETSTORE] for more details on how
to use them.

[SECRETSTORE]: ../../../docs/CONFIGURATION.md#secret-store-secrets

## Configuration

```toml @sample.conf
# Read metrics from Microsoft SQL Server
[[inputs.sqlserver]]
  ## Specify instances to monitor with a list of connection strings.
  ## All connection parameters are optional.
  ## By default, the host is localhost, listening on default port, TCP 1433.
  ##   for Windows, the user is the currently running AD user (SSO).
  ##   See https://github.com/denisenkom/go-mssqldb for detailed connection
  ##   parameters, in particular, tls connections can be created like so:
  ##   "encrypt=true;certificate=<cert>;hostNameInCertificate=<SqlServer host fqdn>"
  servers = [
    "Server=192.168.1.10;Port=1433;User Id=<user>;Password=<pw>;app name=telegraf;log=1;",
  ]

  ## Timeout for query execution operation
  ## Note that the timeout for queries is per query not per gather.
  ## 0 value means no timeout
  # query_timeout = "0s"

  ## Authentication method
  ## valid methods: "connection_string", "AAD"
  # auth_method = "connection_string"

  ## "database_type" enables a specific set of queries depending on the database type. If specified, it replaces azuredb = true/false and query_version = 2
  ## In the config file, the sql server plugin section should be repeated each with a set of servers for a specific database_type.
  ## Possible values for database_type are - "SQLServer" or "AzureSQLDB" or "AzureSQLManagedInstance" or "AzureSQLPool"
  database_type = "SQLServer"

  ## A list of queries to include. If not specified, all the below listed queries are used.
  include_query = []

  ## A list of queries to explicitly ignore.
  exclude_query = ["SQLServerAvailabilityReplicaStates", "SQLServerDatabaseReplicaStates"]

  ## Queries enabled by default for database_type = "SQLServer" are -
  ## SQLServerPerformanceCounters, SQLServerWaitStatsCategorized, SQLServerDatabaseIO, SQLServerProperties, SQLServerMemoryClerks,
  ## SQLServerSchedulers, SQLServerRequests, SQLServerVolumeSpace, SQLServerCpu, SQLServerAvailabilityReplicaStates, SQLServerDatabaseReplicaStates,
  ## SQLServerRecentBackups

  ## Queries enabled by default for database_type = "AzureSQLDB" are -
  ## AzureSQLDBResourceStats, AzureSQLDBResourceGovernance, AzureSQLDBWaitStats, AzureSQLDBDatabaseIO, AzureSQLDBServerProperties,
  ## AzureSQLDBOsWaitstats, AzureSQLDBMemoryClerks, AzureSQLDBPerformanceCounters, AzureSQLDBRequests, AzureSQLDBSchedulers

  ## Queries enabled by default for database_type = "AzureSQLManagedInstance" are -
  ## AzureSQLMIResourceStats, AzureSQLMIResourceGovernance, AzureSQLMIDatabaseIO, AzureSQLMIServerProperties, AzureSQLMIOsWaitstats,
  ## AzureSQLMIMemoryClerks, AzureSQLMIPerformanceCounters, AzureSQLMIRequests, AzureSQLMISchedulers

  ## Queries enabled by default for database_type = "AzureSQLPool" are -
  ## AzureSQLPoolResourceStats, AzureSQLPoolResourceGovernance, AzureSQLPoolDatabaseIO, AzureSQLPoolWaitStats,
  ## AzureSQLPoolMemoryClerks, AzureSQLPoolPerformanceCounters, AzureSQLPoolSchedulers

  ## Queries enabled by default for database_type = "AzureArcSQLManagedInstance" are -
  ## AzureSQLMIDatabaseIO, AzureSQLMIServerProperties, AzureSQLMIOsWaitstats,
  ## AzureSQLMIMemoryClerks, AzureSQLMIPerformanceCounters, AzureSQLMIRequests, AzureSQLMISchedulers

  ## Following are old config settings
  ## You may use them only if you are using the earlier flavor of queries, however it is recommended to use
  ## the new mechanism of identifying the database_type there by use it's corresponding queries

  ## Optional parameter, setting this to 2 will use a new version
  ## of the collection queries that break compatibility with the original
  ## dashboards.
  ## Version 2 - is compatible from SQL Server 2012 and later versions and also for SQL Azure DB
  # query_version = 2

  ## If you are using AzureDB, setting this to true will gather resource utilization metrics
  # azuredb = false

  ## Toggling this to true will emit an additional metric called "sqlserver_telegraf_health".
  ## This metric tracks the count of attempted queries and successful queries for each SQL instance specified in "servers".
  ## The purpose of this metric is to assist with identifying and diagnosing any connectivity or query issues.
  ## This setting/metric is optional and is disabled by default.
  # health_metric = false

  ## Possible queries accross different versions of the collectors
  ## Queries enabled by default for specific Database Type

  ## database_type =  AzureSQLDB  by default collects the following queries
  ## - AzureSQLDBWaitStats
  ## - AzureSQLDBResourceStats
  ## - AzureSQLDBResourceGovernance
  ## - AzureSQLDBDatabaseIO
  ## - AzureSQLDBServerProperties
  ## - AzureSQLDBOsWaitstats
  ## - AzureSQLDBMemoryClerks
  ## - AzureSQLDBPerformanceCounters
  ## - AzureSQLDBRequests
  ## - AzureSQLDBSchedulers

  ## database_type =  AzureSQLManagedInstance by default collects the following queries
  ## - AzureSQLMIResourceStats
  ## - AzureSQLMIResourceGovernance
  ## - AzureSQLMIDatabaseIO
  ## - AzureSQLMIServerProperties
  ## - AzureSQLMIOsWaitstats
  ## - AzureSQLMIMemoryClerks
  ## - AzureSQLMIPerformanceCounters
  ## - AzureSQLMIRequests
  ## - AzureSQLMISchedulers

  ## database_type =  AzureSQLPool by default collects the following queries
  ## - AzureSQLPoolResourceStats
  ## - AzureSQLPoolResourceGovernance
  ## - AzureSQLPoolDatabaseIO
  ## - AzureSQLPoolOsWaitStats,
  ## - AzureSQLPoolMemoryClerks
  ## - AzureSQLPoolPerformanceCounters
  ## - AzureSQLPoolSchedulers

  ## database_type =  SQLServer by default collects the following queries
  ## - SQLServerPerformanceCounters
  ## - SQLServerWaitStatsCategorized
  ## - SQLServerDatabaseIO
  ## - SQLServerProperties
  ## - SQLServerMemoryClerks
  ## - SQLServerSchedulers
  ## - SQLServerRequests
  ## - SQLServerVolumeSpace
  ## - SQLServerCpu
  ## - SQLServerRecentBackups
  ## and following as optional (if mentioned in the include_query list)
  ## - SQLServerAvailabilityReplicaStates
  ## - SQLServerDatabaseReplicaStates

  ## Version 2 by default collects the following queries
  ## Version 2 is being deprecated, please consider using database_type.
  ## - PerformanceCounters
  ## - WaitStatsCategorized
  ## - DatabaseIO
  ## - ServerProperties
  ## - MemoryClerk
  ## - Schedulers
  ## - SqlRequests
  ## - VolumeSpace
  ## - Cpu

  ## Version 1 by default collects the following queries
  ## Version 1 is deprecated, please consider using database_type.
  ## - PerformanceCounters
  ## - WaitStatsCategorized
  ## - CPUHistory
  ## - DatabaseIO
  ## - DatabaseSize
  ## - DatabaseStats
  ## - DatabaseProperties
  ## - MemoryClerk
  ## - VolumeSpace
  ## - PerformanceMetrics
```

## Support for Azure Active Directory (AAD) authentication using [Managed Identity](https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/overview)

- Azure SQL Database supports 2 main methods of authentication: [SQL authentication and AAD authentication](https://docs.microsoft.com/en-us/azure/azure-sql/database/security-overview#authentication).
- The recommended practice is to [use AAD authentication when possible](https://docs.microsoft.com/en-us/azure/azure-sql/database/authentication-aad-overview).

AAD is a more modern authentication protocol, allows for easier
credential/role management, and can eliminate the need to include passwords
in a connection string.

To enable support for AAD authentication, we leverage the existing AAD
authentication support.

- Please see [SQL Server driver for Go](https://github.com/denisenkom/go-mssqldb#azure-active-directory-authentication---preview)

### How to use AAD Auth with MSI

- Please note AAD based auth is currently only supported for Azure SQL Database and Azure SQL Managed Instance (but not for SQL Server), as described [here](https://docs.microsoft.com/en-us/azure/azure-sql/database/security-overview#authentication).

- Configure "system-assigned managed identity" for Azure resources on the Monitoring VM (the VM that'd connect to the SQL server/database) [using the Azure portal](https://docs.microsoft.com/en-us/azure/active-directory/managed-identities-azure-resources/qs-configure-portal-windows-vm).
- On the database being monitored, create/update a USER with the name of the Monitoring VM as the principal using the below script. This might require allow-listing the client machine's IP address (from where the below SQL script is being run) on the SQL Server resource.

```sql
EXECUTE ('IF EXISTS(SELECT * FROM sys.database_principals WHERE name = ''<Monitoring_VM_Name>'')
    BEGIN
        DROP USER [<Monitoring_VM_Name>]
    END')
EXECUTE ('CREATE USER [<Monitoring_VM_Name>] FROM EXTERNAL PROVIDER')
EXECUTE ('GRANT VIEW DATABASE STATE TO [<Monitoring_VM_Name>]')
```

- On the SQL Server resource of the database(s) being monitored, go to "Firewalls and Virtual Networks" tab and allowlist the monitoring VM IP address.
- On the Monitoring VM, update the telegraf config file with the database connection string in the following format. The connection string only provides the server and database name, but no password (since the VM's system-assigned managed identity would be used for authentication). The auth method must be set to "AAD"

```toml
  servers = [
    "Server=<Azure_SQL_Server_Name>.database.windows.net;Port=1433;Database=<Azure_SQL_Database_Name>;app name=telegraf;log=1;",
  ]
  auth_method = "AAD"
```

## Metrics

To provide backwards compatibility, this plugin support two versions of
metrics queries.

**Note**: Version 2 queries are not backwards compatible with the old queries.
Any dashboards or queries based on the old query format will not work with
the new format. The version 2 queries only report raw metrics, no math has
been done to calculate deltas. To graph this data you must calculate deltas
in your dashboarding software.

### Version 1 (query_version=1): This is Deprecated in 1.6, all future development will be under configuration option database_type

The original metrics queries provide:

- *Performance counters*: 1000+ metrics from `sys.dm_os_performance_counters`
- *Performance metrics*: special performance and ratio metrics
- *Wait stats*: wait tasks categorized from `sys.dm_os_wait_stats`
- *Memory clerk*: memory breakdown from `sys.dm_os_memory_clerks`
- *Database size*: databases size trend from `sys.dm_io_virtual_file_stats`
- *Database IO*: databases I/O from `sys.dm_io_virtual_file_stats`
- *Database latency*: databases latency from `sys.dm_io_virtual_file_stats`
- *Database properties*: databases properties, state and recovery model, from `sys.databases`
- *OS Volume*: available, used and total space from `sys.dm_os_volume_stats`
- *CPU*: cpu usage from `sys.dm_os_ring_buffers`

If you are using the original queries all stats have the following tags:

- `servername`:  hostname:instance
- `type`: type of stats to easily filter measurements

### Version 2 (query_version=2): Being deprecated, All future development will be under configuration option database_type

The new (version 2) metrics provide:

- *Database IO*: IO stats from `sys.dm_io_virtual_file_stats`.
- *Memory Clerk*: Memory clerk breakdown from `sys.dm_os_memory_clerks`, most clerks have been given a friendly name.
- *Performance Counters*: A select list of performance counters from `sys.dm_os_performance_counters`. Some of the important metrics included:
  - *Activity*: Transactions/sec/database, Batch requests/sec, blocked processes, + more
  - *Availability Groups*: Bytes sent to replica, Bytes received from replica, Log bytes received, Log send queue, transaction delay, + more
  - *Log activity*: Log bytes flushed/sec, Log flushes/sec, Log Flush Wait Time
  - *Memory*: PLE, Page reads/sec, Page writes/sec, + more
  - *TempDB*: Free space, Version store usage, Active temp tables, temp table creation rate, + more
  - *Resource Governor*: CPU Usage, Requests/sec, Queued Requests, and Blocked tasks per workload group + more
- *Server properties*: Number of databases in all possible states (online, offline, suspect, etc.), cpu count, total physical memory, available physical memory, SQL Server service uptime, SQL Server SPID, and SQL Server version. In the case of Azure SQL relevant properties such as Tier, #Vcores, Memory etc.
- *Wait stats*: Wait time in ms, number of waiting tasks, resource wait time, signal wait time, max wait time in ms, wait type, and wait category. The waits are categorized using the same categories used in Query Store.
- *Schedulers* - This captures `sys.dm_os_schedulers`.
- *SqlRequests* - This captures a snapshot of `sys.dm_exec_requests` and `sys.dm_exec_sessions` that gives you running requests as well as wait types and
  blocking sessions. Telegraf's monitoring request is omitted unless it is a heading blocker. Also includes sleeping sessions with open transactions.
- *VolumeSpace* - uses `sys.dm_os_volume_stats` to get total, used and occupied space on every disk that contains a data or log file. (Note that even if enabled it won't get any data from Azure SQL Database or SQL Managed Instance). It is pointless to run this with high frequency (ie: every 10s), but it won't cause any problem.
- *Cpu* - uses the buffer ring (`sys.dm_os_ring_buffers`) to get CPU data, the table is updated once per minute. (Note that even if enabled it won't get any data from Azure SQL Database or SQL Managed Instance).

  In order to allow tracking on a per statement basis this query produces a
  unique tag for each query.  Depending on the database workload, this may
  result in a high cardinality series.  Reference the FAQ for tips on
  [managing series cardinality][cardinality].

- *Azure Managed Instances*
  - Stats from `sys.server_resource_stats`
  - Resource governance stats from `sys.dm_instance_resource_governance`
- *Azure SQL Database* in addition to other stats
  - Stats from `sys.dm_db_wait_stats`
  - Resource governance stats from `sys.dm_user_db_resource_governance`
  - Stats from `sys.dm_db_resource_stats`

### database_type = "AzureSQLDB"

These are metrics for Azure SQL Database (single database) and are very
similar to version 2 but split out for maintenance reasons, better ability
to test,differences in DMVs:

- *AzureSQLDBDatabaseIO*: IO stats from `sys.dm_io_virtual_file_stats` including resource governance time, RBPEX, IO for Hyperscale.
- *AzureSQLDBMemoryClerks*: Memory clerk breakdown from `sys.dm_os_memory_clerks`.
- *AzureSQLDBResourceGovernance*: Relevant properties indicatign resource limits from `sys.dm_user_db_resource_governance`
- *AzureSQLDBPerformanceCounters*: A select list of performance counters from `sys.dm_os_performance_counters` including cloud specific counters for SQL Hyperscale.
- *AzureSQLDBServerProperties*: Relevant Azure SQL relevant properties from  such as Tier, #Vcores, Memory etc, storage, etc.
- *AzureSQLDBWaitstats*: Wait time in ms from `sys.dm_db_wait_stats`, number of waiting tasks, resource wait time, signal wait time, max wait time in ms, wait type, and wait category. The waits are categorized using the same categories used in Query Store. These waits are collected only as of the end of the a statement. and for a specific database only.
- *AzureSQLOsWaitstats*: Wait time in ms from `sys.dm_os_wait_stats`, number of waiting tasks, resource wait time, signal wait time, max wait time in ms, wait type, and wait category. The waits are categorized using the same categories used in Query Store. These waits are collected as they occur and instance wide
- *AzureSQLDBRequests*: Requests which are blocked or have a wait type from `sys.dm_exec_sessions` and `sys.dm_exec_requests`. Telegraf's monitoring request is omitted unless it is a heading blocker
- *AzureSQLDBSchedulers* - This captures `sys.dm_os_schedulers` snapshots.

### database_type = "AzureSQLManagedInstance"

These are metrics for Azure SQL Managed instance, are very similar to version
2 but split out for maintenance reasons, better ability to test, differences
in DMVs:

- *AzureSQLMIDatabaseIO*: IO stats from `sys.dm_io_virtual_file_stats` including resource governance time, RBPEX, IO for Hyperscale.
- *AzureSQLMIMemoryClerks*: Memory clerk breakdown from `sys.dm_os_memory_clerks`.
- *AzureSQLMIResourceGovernance*: Relevant properties indicatign resource limits from `sys.dm_instance_resource_governance`
- *AzureSQLMIPerformanceCounters*: A select list of performance counters from `sys.dm_os_performance_counters` including cloud specific counters for SQL Hyperscale.
- *AzureSQLMIServerProperties*: Relevant Azure SQL relevant properties such as Tier, #Vcores, Memory etc, storage, etc.
- *AzureSQLMIOsWaitstats*: Wait time in ms from `sys.dm_os_wait_stats`, number of waiting tasks, resource wait time, signal wait time, max wait time in ms, wait type, and wait category. The waits are categorized using the same categories used in Query Store. These waits are collected as they occur and instance wide
- *AzureSQLMIRequests*: Requests which are blocked or have a wait type from `sys.dm_exec_sessions` and `sys.dm_exec_requests`. Telegraf's monitoring request is omitted unless it is a heading blocker
- *AzureSQLMISchedulers*: This captures `sys.dm_os_schedulers` snapshots.

### database_type = "AzureSQLPool"

These are metrics for Azure SQL to monitor resources usage at Elastic Pool
level. These metrics require additional permissions to be collected, please
ensure to check additional setup section in this documentation.

- *AzureSQLPoolResourceStats*: Returns resource usage statistics for the current elastic pool in a SQL Database server. Queried from `sys.dm_resource_governor_resource_pools_history_ex`.
- *AzureSQLPoolResourceGovernance*: Returns actual configuration and capacity settings used by resource governance mechanisms in the current elastic pool. Queried from `sys.dm_user_db_resource_governance`.
- *AzureSQLPoolDatabaseIO*: Returns I/O statistics for data and log files for each database in the pool. Queried from `sys.dm_io_virtual_file_stats`.
- *AzureSQLPoolOsWaitStats*: Returns information about all the waits encountered by threads that executed. Queried from `sys.dm_os_wait_stats`.
- *AzureSQLPoolMemoryClerks*: Memory clerk breakdown from `sys.dm_os_memory_clerks`.
- *AzureSQLPoolPerformanceCounters*: A selected list of performance counters from `sys.dm_os_performance_counters`. Note: Performance counters where the cntr_type column value is 537003264 are already returned with a percentage format between 0 and 100. For other counters, please check [sys.dm_os_performance_counters](https://docs.microsoft.com/en-us/sql/relational-databases/system-dynamic-management-views/sys-dm-os-performance-counters-transact-sql?view=azuresqldb-current) documentation.
- *AzureSQLPoolSchedulers*: This captures `sys.dm_os_schedulers` snapshots.

### database_type = "SQLServer"

- *SQLServerDatabaseIO*: IO stats from `sys.dm_io_virtual_file_stats`
- *SQLServerMemoryClerks*: Memory clerk breakdown from `sys.dm_os_memory_clerks`, most clerks have been given a friendly name.
- *SQLServerPerformanceCounters*: A select list of performance counters from `sys.dm_os_performance_counters`. Some of the important metrics included:
  - *Activity*: Transactions/sec/database, Batch requests/sec, blocked processes, + more
  - *Availability Groups*: Bytes sent to replica, Bytes received from replica, Log bytes received, Log send queue, transaction delay, + more
  - *Log activity*: Log bytes flushed/sec, Log flushes/sec, Log Flush Wait Time
  - *Memory*: PLE, Page reads/sec, Page writes/sec, + more
  - *TempDB*: Free space, Version store usage, Active temp tables, temp table creation rate, + more
  - *Resource Governor*: CPU Usage, Requests/sec, Queued Requests, and Blocked tasks per workload group + more
- *SQLServerProperties*: Number of databases in all possible states (online, offline, suspect, etc.), cpu count, total physical memory, available physical memory, SQL Server service uptime, SQL Server SPID and SQL Server version. In the case of Azure SQL relevant properties such as Tier, #Vcores, Memory etc.
- *SQLServerWaitStatsCategorized*: Wait time in ms, number of waiting tasks, resource wait time, signal wait time, max wait time in ms, wait type, and wait category. The waits are categorized using the same categories used in Query Store.
- *SQLServerSchedulers*: This captures `sys.dm_os_schedulers`.
- *SQLServerRequests*: This captures a snapshot of `sys.dm_exec_requests` and `sys.dm_exec_sessions` that gives you running requests as well as wait types and
  blocking sessions.
- *SQLServerVolumeSpace*: Uses `sys.dm_os_volume_stats` to get total, used and occupied space on every disk that contains a data or log file. (Note that even if enabled it won't get any data from Azure SQL Database or SQL Managed Instance). It is pointless to run this with high frequency (ie: every 10s), but it won't cause any problem.
- SQLServerCpu: Uses the buffer ring (`sys.dm_os_ring_buffers`) to get CPU data, the table is updated once per minute. (Note that even if enabled it won't get any data from Azure SQL Database or SQL Managed Instance).
- SQLServerAvailabilityReplicaStates: Collects availability replica state information from `sys.dm_hadr_availability_replica_states` for a High Availability / Disaster Recovery (HADR) setup
- SQLServerDatabaseReplicaStates: Collects database replica state information from `sys.dm_hadr_database_replica_states` for a High Availability / Disaster Recovery (HADR) setup
- SQLServerRecentBackups: Collects latest full, differential and transaction log backup date and size from `msdb.dbo.backupset`

### Output Measures

The guiding principal is that all data collected from the same primary DMV ends
up in the same measure irrespective of database_type.

- `sqlserver_database_io` - Used by  AzureSQLDBDatabaseIO, AzureSQLMIDatabaseIO, SQLServerDatabaseIO, DatabaseIO given the data is from `sys.dm_io_virtual_file_stats`
- `sqlserver_waitstats` - Used by  WaitStatsCategorized,AzureSQLDBOsWaitstats,AzureSQLMIOsWaitstats
- `sqlserver_server_properties` - Used by  SQLServerProperties, AzureSQLDBServerProperties , AzureSQLMIServerProperties,ServerProperties
- `sqlserver_memory_clerks` - Used by SQLServerMemoryClerks, AzureSQLDBMemoryClerks, AzureSQLMIMemoryClerks,MemoryClerk
- `sqlserver_performance` - Used by  SQLServerPerformanceCounters, AzureSQLDBPerformanceCounters, AzureSQLMIPerformanceCounters,PerformanceCounters
- `sys.dm_os_schedulers`  - Used by SQLServerSchedulers,AzureSQLDBServerSchedulers, AzureSQLMIServerSchedulers

The following Performance counter metrics can be used directly, with no delta
calculations:

- SQLServer:Buffer Manager\Buffer cache hit ratio
- SQLServer:Buffer Manager\Page life expectancy
- SQLServer:Buffer Node\Page life expectancy
- SQLServer:Database Replica\Log Apply Pending Queue
- SQLServer:Database Replica\Log Apply Ready Queue
- SQLServer:Database Replica\Log Send Queue
- SQLServer:Database Replica\Recovery Queue
- SQLServer:Databases\Data File(s) Size (KB)
- SQLServer:Databases\Log File(s) Size (KB)
- SQLServer:Databases\Log File(s) Used Size (KB)
- SQLServer:Databases\XTP Memory Used (KB)
- SQLServer:General Statistics\Active Temp Tables
- SQLServer:General Statistics\Processes blocked
- SQLServer:General Statistics\Temp Tables For Destruction
- SQLServer:General Statistics\User Connections
- SQLServer:Memory Broker Clerks\Memory broker clerk size
- SQLServer:Memory Manager\Memory Grants Pending
- SQLServer:Memory Manager\Target Server Memory (KB)
- SQLServer:Memory Manager\Total Server Memory (KB)
- SQLServer:Resource Pool Stats\Active memory grant amount (KB)
- SQLServer:Resource Pool Stats\Disk Read Bytes/sec
- SQLServer:Resource Pool Stats\Disk Read IO Throttled/sec
- SQLServer:Resource Pool Stats\Disk Read IO/sec
- SQLServer:Resource Pool Stats\Disk Write Bytes/sec
- SQLServer:Resource Pool Stats\Disk Write IO Throttled/sec
- SQLServer:Resource Pool Stats\Disk Write IO/sec
- SQLServer:Resource Pool Stats\Used memory (KB)
- SQLServer:Transactions\Free Space in tempdb (KB)
- SQLServer:Transactions\Version Store Size (KB)
- SQLServer:User Settable\Query
- SQLServer:Workload Group Stats\Blocked tasks
- SQLServer:Workload Group Stats\CPU usage %
- SQLServer:Workload Group Stats\Queued requests
- SQLServer:Workload Group Stats\Requests completed/sec

Version 2 queries have the following tags:

- `sql_instance`: Physical host and instance name (hostname:instance)
- `database_name`:  For Azure SQLDB, database_name denotes the name of the Azure SQL Database as server name is a logical construct.

### Health Metric

All collection versions (version 1, version 2, and database_type) support an
optional plugin health metric called `sqlserver_telegraf_health`. This metric
tracks if connections to SQL Server are succeeding or failing. Users can
leverage this metric to detect if their SQL Server monitoring is not working
as intended.

In the configuration file, toggling `health_metric` to `true` will enable
collection of this metric. By default, this value is set to `false` and
the metric is not collected. The health metric emits one record for each
connection specified by `servers` in the configuration file.

The health metric emits the following tags:

- `sql_instance` - Name of the server specified in the connection string. This value is emitted as-is in the connection string. If the server could not be parsed from the connection string, a constant placeholder value is emitted
- `database_name` -  Name of the database or (initial catalog) specified in the connection string. This value is emitted as-is in the connection string. If the database could not be parsed from the connection string, a constant placeholder value is emitted

The health metric emits the following fields:

- `attempted_queries` - Number of queries that were attempted for this connection
- `successful_queries` - Number of queries that completed successfully for this connection
- `database_type` - Type of database as specified by `database_type`. If `database_type` is empty, the `QueryVersion` and `AzureDB` fields are concatenated instead

If `attempted_queries` and `successful_queries` are not equal for
a given connection, some metrics were not successfully gathered for
that connection. If `successful_queries` is 0, no metrics were successfully
gathered.

[cardinality]: /docs/FAQ.md#user-content-q-how-can-i-manage-series-cardinality

## Example Output

```text
sqlserver_cpu_other_process_cpu{host="servername",measurement_db_type="SQLServer",sql_instance="SERVERNAME:INST"} 9
sqlserver_performance{counter="Log File(s) Size (KB)",counter_type="65792",host="servername",instance="instance_name",measurement_db_type="SQLServer",object="MSSQL$INSTANCE_NAME:Databases",sql_instance="SERVERNAME:INSTANCE_NAME"} 1.048568e+06
```
