Nonhashable data types

For opaque types that are not bit hashable using the built-in hashing function of the database server, specify the CANNOTHASH modifier in the CREATE OPAQUE TYPE statement.

Hashable data types have the following property: if A = B, then hash(A) = hash(B), which means that A and B have identical bit representations.

Multirepresentational data types are not bit hashable because they store large quantities of data in a smart large object and then store the large object handle in the user-defined type. It is the smart-large-object handle that makes the multirepresentational data type nonhashable. That is, the CREATE OPAQUE TYPE statement for a multirepresentational data type must include the CANNOTHASH modifier.