SQL Re-Compilation

Microsoft.SQLServer.Windows.Monitor.DBEngine.SQLRecompilation (UnitMonitor)

SQL Re-Compilation for DB Engine. Note that this monitor is disabled by default. Use overrides to enable it when necessary.

Knowledge Base article:

Summary

SQL Re-Compilation monitor for SQL DB Engine

Certain changes in a database can cause an execution plan to be either inefficient or invalid, based on the new state of the database. SQL Server detects the changes that invalidate an execution plan and marks the plan as not valid. A new plan must then be recompiled for the next connection that executes the query.

Causes

High number of recompilations comparing to compilations.

Resolutions

Start SQL Profiler and check SQL:StmtRecompile trace to identify root cause of issue.

Overridable Parameters

Name	Description	Default Value
Alert Priority	Defines Alert Priority.	Normal
Alert Severity	Defines Alert Severity.	Warning
Enabled	Enables or disables the workflow.	No
Generates Alerts	Defines whether the workflow generates an Alert.	Yes
Interval (seconds)	The recurring interval of time in seconds in which to run the workflow.	300
Number of samples	Indicates how many times a measured value should breach a threshold before the state is changed.	6
Synchronization Time	The synchronization time specified by using a 24-hour format. May be omitted.
Threshold	If the ratio between SQL Re-Compilation and SQL Compilation is greater than this threshold alert will be generated.	25
Timeout (seconds)	Specifies the time the workflow is allowed to run before being closed and marked as failed.	200
Timeout for query execution (seconds)	The workflow will fail and register an event, if the query execution takes longer than the specified period.	60
Timeout for database connection (seconds)	The workflow will fail and register an event, if it cannot access the database during the specified period.	15

Element properties:

Target

Microsoft.SQLServer.Windows.DBEngine

Parent Monitor

System.Health.PerformanceState

Category

PerformanceHealth

Enabled

False

Alert Generate

True

Alert Severity

Warning

Alert Priority

Normal

Alert Auto Resolve

True

Monitor Type

Microsoft.SQLServer.Windows.MonitorType.DBEngine.SQLRecompilation

Remotable

True

Accessibility

Public

Alert Message

MSSQL on Windows: SQL Re-Compilation is too high

SQL re-compilation on SQL Server instance "{1}", computer "{0}" is too high. See the "Alert Context" tab for more details.

RunAs

Default

Source Code:

<UnitMonitor ID="Microsoft.SQLServer.Windows.Monitor.DBEngine.SQLRecompilation" Accessibility="Public" Enabled="false" Target="SqlDiscW!Microsoft.SQLServer.Windows.DBEngine" ParentMonitorID="Health!System.Health.PerformanceState" Remotable="true" Priority="Normal" TypeID="Microsoft.SQLServer.Windows.MonitorType.DBEngine.SQLRecompilation" ConfirmDelivery="false">

  <Category>PerformanceHealth</Category>

  <AlertSettings AlertMessage="Microsoft.SQLServer.Windows.Monitor.DBEngine.SQLRecompilation.AlertMessage">

    <AlertOnState>Warning</AlertOnState>

    <AutoResolve>true</AutoResolve>

    <AlertPriority>Normal</AlertPriority>

    <AlertSeverity>Warning</AlertSeverity>

    <AlertParameters>

      <AlertParameter1>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/MachineName$</AlertParameter1>

      <AlertParameter2>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/InstanceName$</AlertParameter2>

    </AlertParameters>

  </AlertSettings>

  <OperationalStates>

    <OperationalState ID="Normal" MonitorTypeStateID="Normal" HealthState="Success"/>

    <OperationalState ID="Error" MonitorTypeStateID="Error" HealthState="Warning"/>

  </OperationalStates>

  <Configuration>

    <MachineName>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/MachineName$</MachineName>

    <NetbiosComputerName>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/NetbiosComputerName$</NetbiosComputerName>

    <InstanceName>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/InstanceName$</InstanceName>

    <ConnectionString>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/ConnectionString$</ConnectionString>

    <InstanceVersion>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/Version$</InstanceVersion>

    <InstanceEdition>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/Edition$</InstanceEdition>

    <MonitoringType>$Target/Property[Type="SqlDiscW!Microsoft.SQLServer.Windows.DBEngine"]/MonitoringType$</MonitoringType>

    <PerformanceCounterObject>$Target/Property[Type="SqlCoreLib!Microsoft.SQLServer.Core.DBEngine"]/PerformanceCounterObject$</PerformanceCounterObject>

    <Threshold>25</Threshold>

    <NumSamples>6</NumSamples>

    <SqlExecTimeoutSeconds>60</SqlExecTimeoutSeconds>

    <SqlTimeoutSeconds>15</SqlTimeoutSeconds>

    <TimeoutSeconds>200</TimeoutSeconds>

    <IntervalSeconds>300</IntervalSeconds>

    <SyncTime/>

  </Configuration>

</UnitMonitor>