Partial Key 2

The number of unique key values from the first two key fields for keyed access paths. If the access path is an encoded vector, this number represents the number of full key distinct values. If this value is zero, then the unique key statistics are not available for this partial key. This number is not available for access paths restored from previous releases, containing only 1 key field, are encoded vector, have keys which contain varying length character fields, or have multiple based-on files.