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<h1>Indexes</h1>
<p>One more feature that inevitably decreases the insert performance:
indexes. When a new object with indexed field is inserted an index should be
created and written to the database, which consumes additional resources.
Luckily indexes do not only reduce the performance, actually they will improve
the performance to a much more valuable degree during querying.</p>
<p>An example below provides a simple comparison of storing
objects with and without indexes:</p>
<p MadCap:conditions="Global.Primary:java" />
<p MadCap:conditions="Primary..NET">
<pre class="prettyprint" xml:space="preserve">InsertPerformanceBenchmark.cs: RunIndexTest
private void RunIndexTest()
{
Init();
System.Console.WriteLine("Storing " + _count + " objects with "
+ _depth + " levels of embedded objects:");
Clean();
Configure();
System.Console.WriteLine(" - no index");
Open();
Store();
Close();
ConfigureIndex();
System.Console.WriteLine(" - index on String field");
Open();
Store();
Close();
}</pre>
<pre class="prettyprint" xml:space="preserve">InsertPerformanceBenchmark.cs: Configure
private void Configure()
{
IConfiguration config = Db4oFactory.Configure();
config.LockDatabaseFile(false);
config.WeakReferences(false);
config.Io(new MemoryIoAdapter());
config.FlushFileBuffers(false);
}</pre>
<pre class="prettyprint" xml:space="preserve">InsertPerformanceBenchmark.cs: ConfigureIndex
private void ConfigureIndex()
{
IConfiguration config = Db4oFactory.Configure();
config.LockDatabaseFile(false);
config.WeakReferences(false);
config.Io(new MemoryIoAdapter());
config.FlushFileBuffers(false);
config.ObjectClass(typeof(Item)).ObjectField("_name").Indexed(true);
}</pre>
<pre class="prettyprint" xml:space="preserve">InsertPerformanceBenchmark.cs: Init
private void Init()
{
_count = 10000;
_depth = 3;
_isClientServer = false;
}</pre>
<pre class="prettyprint" xml:space="preserve">InsertPerformanceBenchmark.cs: Store
private void Store()
{
StartTimer();
for (int i = 0; i < _count; i++)
{
Item item = new Item("load", null);
for (int j = 1; j < _depth; j++)
{
item = new Item("load", item);
}
objectContainer.Store(item);
}
objectContainer.Commit();
StopTimer("Store " + TotalObjects() + " objects");
}</pre>
</p>
<p MadCap:conditions="Global.Primary:net" />
<p>The following results were achieved for the
<a href="../insert_performance.htm">testing configuration</a>:</p>
<p MadCap:conditions="Global.Primary:java" />
<p MadCap:conditions="Primary..NET">
<p>.NET:</p>
<p>Storing 10000 objects with 3 levels of embedded objects:</p>
<p> - no index</p>
<p>Store 30000 objects: 1235ms</p>
<p> - index on String
field</p>
<p>Store 30000 objects: 1748ms </p>
</p>
<p MadCap:conditions="Global.Primary:net" />
<p MadCap:conditions="Primary.Online">Download example code:</p>
<p MadCap:conditions="Primary.Online">
<MadCap:conditionalText MadCap:conditions="Primary..NET,Primary.c#,Primary.All languages"><a href="../performancecs.zip">c# </a>
</MadCap:conditionalText>
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