Index Columns

The IndexColumns schema collection lists the indexes and their corresponding columns. By filtering on indexes, you can write more selective queries with faster query response times.

Retrieving Index Column Information

To retrieve this schema collection, call the GetSchema method of the CompositeConnection class. You can restrict the results by table name. The following example retrieves the column and sequence number for each index of the TDV table Products.

C#

String connectionString = "Host=myHost;Domain=myDomain;DataSource=myDataSource;User=myUser;Password=myPassword";

using (CompositeConnection conn = new CompositeConnection(connectionString)) {

  conn.Open();

  DataTable databaseSchema = conn.GetSchema("IndexColumns", new string[] {"Products"});

  foreach (DataRow row in databaseSchema.Rows) {

    Console.WriteLine(row["COLUMN_NAME"]);

    Console.WriteLine(row["ORDINAL_POSITION"]);

  }

}

VB.NET

Dim connectionString As String = "Host=myHost;Domain=myDomain;DataSource=myDataSource;User=myUser;Password=myPassword"

Using conn As New CompositeConnection(connectionString)

  conn.Open()

  Dim databaseSchema As DataTable = conn.GetSchema("IndexColumns",  New String() {"Products"})

  For Each row As DataRow In databaseSchema.Rows

    Console.WriteLine(row["COLUMN_NAME"])

    Console.WriteLine(row["ORDINAL_POSITION"])

  Next

End Using

Columns Returned

The IndexColumns schema collection returns the following columns:

Column Name	Data Type	Description
INDEX_CATALOG	System.String	The name of the database containing the index.
INDEX_SCHEMA	System.String	The name of the schema containing the index.
TABLE_NAME	System.String	The name of the table containing the index.
INDEX_NAME	System.String	The name of the index.
COLUMN_NAME	System.String	The name of the column associated with the index.
ORDINAL_POSITION	System.Int32	The sequence number of the column.
SORT_ORDER	System.Int32	Returns A for ascending and D for descending.