IndexedAttribute Class
Indicates that a property or field participates in index creation.
Namespace: DevExpress.Xpo
Assembly: DevExpress.Xpo.v19.2.dll
Declaration
Remarks
The IndexedAttribute attribute indicates that a table (or another form of data store) will have an index for the column(s). An index allows a database to find data in a table without scanning the entire table. Indexes can be created on either a single property (column) or a combination of properties (columns). For more information on multi-column (compound) indexes, refer to the IndexedAttribute.AdditionalFields property description.
Note
XPO does not support tables with multi-column (compound) keys or indexes in ASE databases. To avoid exceptions when connecting to ASE databases containing these tables, use one-column keys or indexes.
For instance, you can apply the IndexedAttribute attribute to a persistent property to make it unique (see the example below):
public class User : XPObject {
[Indexed(Unique = true)]
public int UserId {
get { return fUserId; }
set { SetPropertyValue(nameof(UserId), ref fUserId, value); }
}
int fUserId;
public string UserName {
get { return fUserName; }
set { SetPropertyValue(nameof(UserName), ref fUserName, value); }
}
string fUserName;
}
To define several non-unique database indices, use IndicesAttribute.