# Nullable Fields and Indexes

> Note that nulls are not included into indexes. In other words, if a `nullable` field is indexed, and an object of the class has the null indicator set to true for that field, that object will not be included in the index. Therefore, take care that there is some other access method other than through an index on a `nullable` field(s). For example, consider a schema like the following:

>         C/C++/Python:

>         class Record
>         {
>             nullable uint4 id;
>             string  name;

>             tree<id> by_id;
>         };

>         Java:

>         class Record
>         {
>             @Indexable(unique=true)
>             @nullable
>             int id;

>             public String name;
>         }

>         C#:

>         class Record
>         {
>             [Indexable(Unique=true)]
>             public int? id;

>             public String name;
>         }

> Any objects of class `Record` with the `null` indicator set for `id` will be inaccessible. As soon as the `null` indicator is set and the transaction committed, the object will be removed from the index. With no other access method to locate the object, it becomes inaccessible.

> Also, note that although an index on a nullable field can be used for lookups, this index can not be used for sorting objects by this field. And nullable fields cannot be included in compound indexes.