sp_dbmmonitorhelpalert (Transact-SQL)

Article
02/28/2023

Applies to: SQL Server

Returns information about warning thresholds on one or all of several key database mirroring monitor performance metrics.

Transact-SQL syntax conventions

Syntax

  
sp_dbmmonitorhelpalert database_name   
    [ , alert_id ]

Arguments

database_name
Specifies the database.

[ alert_id ]
An integer value that identifies the warning to be returned. If this argument is omitted, all the warnings are returned, but not the retention period.

To return a specific warning, specify one of the following values:

Value	Performance metric	Warning threshold
1	Oldest unsent transaction	Specifies the number of minutes worth of transactions that can accumulate in the send queue before a warning is generated on the principal server instance. This warning helps measure the potential for data loss in terms of time, and it is particularly relevant for high-performance mode. However, the warning is also relevant for high-safety mode when mirroring is paused or suspended because the partners become disconnected.
2	Unsent log	Specifies how many kilobytes (KB) of unsent log generate a warning on the principal server instance. This warning helps measure the potential for data loss in terms of KB, and it is particularly relevant for high-performance mode. However, the warning is also relevant for high-safety mode when mirroring is paused or suspended because the partners become disconnected.
3	Unrestored log	Specifies how many KB of unrestored log generate a warning on the mirror server instance. This warning helps measure failover time. Failover time consists mainly of the time that the former mirror server requires to roll forward any log remaining in its redo queue, plus a short additional time.
4	Mirror commit overhead	Specifies the number of milliseconds of average delay per transaction that are tolerated before a warning is generated on the principal server. This delay is the amount of overhead incurred while the principal server instance waits for the mirror server instance to write the transaction's log record into the redo queue. This value is relevant only in high-safety mode.
5	Retention period	Metadata that controls how long rows in the database mirroring status table are preserved.

For information about the event IDs corresponding to the warnings, see Use Warning Thresholds and Alerts on Mirroring Performance Metrics (SQL Server).

Return Code Values

None

Result Sets

For each returned alert, returns a row containing the following columns:

Column	Data type	Description
alert_id	int	The table below lists the alert_id value for each performance metric and the unit of measurement of the metric displayed in the sp_dbmmonitorresults result set:
threshold	int	The threshold value for the warning. If a value above this threshold is returned when the mirroring status is updated, an entry is entered into the Windows event log. This value represents KB, minutes, or milliseconds, depending on the warning. If the threshold is currently not set, the value is NULL. Note: To view the current values, run the sp_dbmmonitorresults stored procedure.
enabled	bit	0 = Event is disabled. 1 = Event is enabled. Note: Retention period is always enabled.

Value	Performance metric	Unit
1	Oldest unsent transaction	Minutes
2	Unsent log	KB
3	Unrestored log	KB
4	Mirror commit overhead	Milliseconds
5	Retention period	Hours

Permissions

Requires membership in the sysadmin fixed server role.

Examples

The following example returns a row that indicates whether a warning is enabled for the oldest unsent transaction performance metric on the AdventureWorks2022 database.

EXEC sp_dbmmonitorhelpalert AdventureWorks2022, 1 ;

The following example returns a row for each performance metric that indicates whether it is enabled on the AdventureWorks2022 database.

EXEC sp_dbmmonitorhelpalert AdventureWorks2022;