Compare (CMP) Index

A Compare (CMP) index is the relationship between two columns. You may create Compare indexes on any two distinct columns with identical data types, precision, and scale. The CMP index stores the binary comparison (<, >, or =) of its two columns.

• Recommended Use of CMP
  You can create a CMP index on columns that are NULL, NOT NULL, or a mixture. The CMP index cannot be unique.
• Restrictions on CMP Indexes
  The following restrictions apply to CMP.