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<h1><a name="kanchor14"></a>Monitoring Optimization</h1>
<p>In order to optimize native queries the <span class="PrimaryByteCode">bytecode</span> is analyzed and converted into <a href="../../soda_query.htm">SODA queries</a>. This task isn't easy. If there's any doubt in the correctness of the conversion db4o won't do it. In such cases db4o falls back and instantiates all objects and runs it against the query. This is a order of magnitude slower than optimized queries. Therefore you probably want to monitor the query optimization and be warned when a query isn't optimized. This is possible with the <a href="../../../../tuning/diagnostics.htm">diagnostic listeners</a>.</p>
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<pre class="prettyprint" xml:space="preserve">configuration.Common.Diagnostic.AddListener(new NativeQueryListener());</pre>
<div class="codesnippet-meta">NativeQueryDiagnostics.cs: Use diagnostics to find unoptimized queries
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<pre class="prettyprint lang-vb" MadCap:conditions="Primary.Online" xml:space="preserve">configuration.Common.Diagnostic.AddListener(New NativeQueryListener())</pre>
<div class="codesnippet-meta">NativeQueryDiagnostics.vb: Use diagnostics to find unoptimized queries
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<pre class="prettyprint" xml:space="preserve">class NativeQueryListener :IDiagnosticListener
{
public void OnDiagnostic(IDiagnostic diagnostic)
{
if(diagnostic is NativeQueryNotOptimized){
Console.WriteLine("Query not optimized"+diagnostic);
} else if(diagnostic is NativeQueryOptimizerNotLoaded){
Console.WriteLine("Missing native query optimisation assemblies" + diagnostic);
}
}
}</pre>
<div class="codesnippet-meta">NativeQueryDiagnostics.cs: The native query listener
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<pre class="prettyprint lang-vb" MadCap:conditions="Primary.Online" xml:space="preserve">Class NativeQueryListener
Implements IDiagnosticListener
Public Sub OnDiagnostic(ByVal diagnostic As IDiagnostic) Implements IDiagnosticListener.OnDiagnostic
If TypeOf diagnostic Is NativeQueryNotOptimized Then
Console.WriteLine("Query not optimized" & Convert.ToString(diagnostic))
ElseIf TypeOf diagnostic Is NativeQueryOptimizerNotLoaded Then
Console.WriteLine("Missing native query optimisation assemblies" & Convert.ToString(diagnostic))
End If
End Sub
End Class</pre>
<div class="codesnippet-meta">NativeQueryDiagnostics.vb: The native query listener
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<p>You can register a diagnostic listener and check for certain messages. There are two messages related to the native query optimization. The first is the <strong>NativeQueryNotOptimized</strong>-message. This tells you that a query couldn't be optimized. Consider simplifying the query. The second is the <strong>NativeQueryOptimizerNotLoaded</strong>-message. This message tells you that db4o couldn't find the libraries needed for the native query optimization. Check that you've included the <span class="PrimaryArtefacts">assemblies</span>-files <a href="../../../../dependency_overview.htm">you need</a>. </p>
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