Working with indexes

In this topic

• About working with indexes
• Attribute indexes
• Spatial indexes

About working with indexes

public void DisplayIndexCount(ITable table)
{
    IIndexes indexes=table.Indexes;
    Console.WriteLine("The table has an index count of {0}.", indexes.IndexCount);
}

Public Sub DisplayIndexCount(ByVal table As ITable)
    
    Dim indexes As IIndexes=table.Indexes
    Console.WriteLine("The table has an index count of {0}.", indexes.IndexCount)
    
End Sub

Attribute indexes

// This method displays the fields associated with each class's indexes.
public void DisplayAttributeIndexFields(IFeatureClass featureClass)
{
    // Get the collection of indexes.
    IIndexes indexes=featureClass.Indexes;

    // Iterate through the indexes.
    for (int i=0; i < indexes.IndexCount; i++)
    {
        // Get the fields collection and first field of the index.
        IIndex index=indexes.get_Index(i);
        IFields fields=index.Fields;
        IField field=fields.get_Field(0);

        // If the field isn't a shape field, display the index's name and its fields.
        if (field.Type != esriFieldType.esriFieldTypeGeometry)
        {
            Console.WriteLine("Index Name: {0}", index.Name);
            for (int j=0; j < fields.FieldCount; j++)
            {
                field=fields.get_Field(j);
                Console.WriteLine("Associated Field {0}: {1}", j, field.Name);
            }
        }
    }
}

' This method displays the fields associated with each class's indexes.

Public Sub DisplayAttributeIndexFields(ByVal featureClass As IFeatureClass)
    
    ' Get the collection of indexes.
    Dim indexes As IIndexes=featureClass.Indexes
    
    ' Iterate through the indexes.
    For i As Integer=0 To indexes.IndexCount - 1
        ' Get the fields collection and first field of the index.
        Dim index As IIndex=indexes.Index(i)
        Dim fields As IFields=index.Fields
        Dim field As IField=fields.Field(0)
        
        ' If the field isn't a shape field, display the index's name and its fields.
        If field.Type <> esriFieldType.esriFieldTypeGeometry Then
            Console.WriteLine("Index Name: {0}", index.Name)
            
            For j As Integer=0 To fields.FieldCount - 1
                field=fields.Field(j)
                Console.WriteLine("Associated Field {0}: {1}", j, field.Name)
            Next j
            
        End If
    Next i
    
End Sub

public void DeleteIndexesByFieldName(IFeatureClass featureClass, String nameOfField)
{
    // Find all indexes associated with a specific field.
    IIndexes indexes=featureClass.Indexes;
    IEnumIndex enumIndex=indexes.FindIndexesByFieldName(nameOfField);

    // Attempt to acquire an exclusive schema lock on the feature class.
    ISchemaLock schemaLock=(ISchemaLock)featureClass;
    try
    {
        schemaLock.ChangeSchemaLock(esriSchemaLock.esriExclusiveSchemaLock);

        // Iterate through and delete returned indexes.
        IIndex index=null;
        while ((index=enumIndex.Next()) != null)
        {
            featureClass.DeleteIndex(index);
        }
    }
    catch (COMException comExc)
    {
        // Handle appropriately for your application.
        Console.WriteLine("A COM Exception was thrown: {0}", comExc.Message);
    }
    finally
    {
        schemaLock.ChangeSchemaLock(esriSchemaLock.esriSharedSchemaLock);
    }
}

Public Sub DeleteIndexesByFieldName(ByVal featureClass As IFeatureClass, ByVal nameOfField As String)
    
    ' Find all indexes associated with a specific field.
    Dim indexes As IIndexes=featureClass.Indexes
    Dim enumIndex As IEnumIndex=indexes.FindIndexesByFieldName(nameOfField)
    
    ' Attempt to acquire an exclusive schema lock on the feature class.
    Dim schemaLock As ISchemaLock=CType(featureClass, ISchemaLock)
    Try
    schemaLock.ChangeSchemaLock(esriSchemaLock.esriExclusiveSchemaLock)
    ' Iterate through and delete returned indexes.
    Dim index As IIndex=Nothing
    Do While Not (index) Is Nothing
        featureClass.DeleteIndex(index)
        index=enumIndex.Next()
    Loop
    Catch comExc As COMException
    ' Handle appropriately for your application.
    Console.WriteLine("A COM Exception was thrown: {0}", comExc.Message)
    Finally
    schemaLock.ChangeSchemaLock(esriSchemaLock.esriSharedSchemaLock)
    End Try
    
End Sub

public IIndex GetIndexByName(IIndexes indexes, String indexName)
{
    int indexPosition= - 1;
    indexes.FindIndex(indexName, out indexPosition);
    IIndex index=indexes.get_Index(indexPosition);
    return index;
}

Public Function GetIndexByName(ByVal indexes As IIndexes, ByVal indexName As String) As IIndex
    
    Dim indexPosition As Integer=-1
    indexes.FindIndex(indexName, indexPosition)
    Dim index As IIndex=indexes.Index(indexPosition)
    
    Return index
    
End Function

Spatial indexes

public void DisplaySpatialIndexProperties(IFeatureClass featureClass)
{
    // Find the shape field from the class's field set.
    String shapeFieldName=featureClass.ShapeFieldName;
    int shapeFieldIndex=featureClass.FindField(shapeFieldName);
    IFields fields=featureClass.Fields;
    IField shapeField=fields.get_Field(shapeFieldIndex);

    // Get the name of the spatial index, if one exists.
    IIndexes indexes=featureClass.Indexes;
    IEnumIndex enumIndex=indexes.FindIndexesByFieldName(shapeFieldName);
    enumIndex.Reset();
    IIndex spatialIndex=enumIndex.Next();
    if (spatialIndex == null)
    {
        Console.WriteLine("No spatial index exists.");
        return ;
    }
    Console.WriteLine("Spatial index name: {0}", spatialIndex.Name);

    // Get the shape field's GeometryDef and inspect its properties.
    IGeometryDef geometryDef=shapeField.GeometryDef;
    int gridCount=geometryDef.GridCount;
    Console.WriteLine("Grid count: {0}", gridCount);
    for (int i=0; i < gridCount; i++)
    {
        double gridSize=geometryDef.get_GridSize(i);
        Console.WriteLine("Grid[{0}] size: {1}", i, gridSize);
    }
}

Public Sub DisplaySpatialIndexProperties(ByVal featureClass As IFeatureClass)
    ' Find the shape field from the class's field set.
    Dim shapeFieldName As String=featureClass.ShapeFieldName
    Dim shapeFieldIndex As Integer=featureClass.FindField(shapeFieldName)
    Dim fields As IFields=featureClass.Fields
    Dim shapeField As IField=fields.Field(shapeFieldIndex)
    
    ' Get the name of the spatial index, if one exists.
    Dim indexes As IIndexes=featureClass.Indexes
    Dim enumIndex As IEnumIndex=indexes.FindIndexesByFieldName(shapeFieldName)
    enumIndex.Reset()
    Dim spatialIndex As IIndex=enumIndex.Next()
    If spatialIndex Is Nothing Then
        Console.WriteLine("No spatial index exists.")
        Return
    End If
    Console.WriteLine("Spatial index name: {0}", spatialIndex.Name)
    
    ' Get the shape field's GeometryDef and inspect its properties.
    Dim geometryDef As IGeometryDef=shapeField.GeometryDef
    Dim gridCount As Integer=geometryDef.GridCount
    Console.WriteLine("Grid count: {0}", gridCount)
    Dim i As Integer
    For i=0 To gridCount - 1
        Dim gridSize As Double=geometryDef.GridSize(i)
        Console.WriteLine("Grid[{0}] size: {1}", i, gridSize)
    Next i
End Sub

See Also:

• ESRI.ArcGIS.System (ESRI.ArcGIS.esriSystem)
• ESRI.ArcGIS.Geodatabase