Granting or Denying Access to Fields with Access-Control Expressions

For an explanation of the syntax of ACEs, see Syntax of Access Control Expressions.

Traverse (traverseperm)

This permission allows the grantee to descend a hierarchy of fields to access the fields that the grantee has write or read permission on.

For example, suppose that a user has read and write access only on field b in this document.

To access field b, the user would need to be able to traverse (pass through) field a. In this case, because the entire document is in the default column family, the user could be granted traverse permission on the default column family. Field a would inherit the traverse permission.

If traverse permission on the default column family were denied the user, it would not be possible for the user to access field b. Granting traverse permission on field a in this case would have no effect.

In the next example, field a is a column family named cf1.

To be able to read and write at field b, the user could be granted the traverse permission on the column family.

Read (readperm)

This permission allows the grantee to read from a field.

This permission extends to fields that are nested below the field that the permission was granted on. However, grantees can be explicitly denied the permission on any of the nested fields.

Write (writeperm)

This permission allows the grantee to delete a field, insert a value into a field, or overwrite a field's value.

As illustrated in the following two diagrams, deleting a field also deletes all fields that are nested within that field, even those fields on which the write permission is explicitly denied.