All ASE datatypes are supported by Mirror Replication Agent. The following is additional information for two of the datatypes, encrypted columns and computed columns:
Encrypted columns – the ability to encrypt most columns as they are stored on disk. Keys and some indexing may not be encrypted. The logged data is ciphertext (encrypted), and transmitted to Replication Server as ciphertext. An option to insert data already encrypted has been added, enabling the data to be transmitted in an image form to the standby database.
Computed columns – defined by an expression, whether from regular columns in the same row, functions, arithmetic operators, or path names. Computed columns are different from function based indexes in the following ways:
A computed column provides a shorthand for an expression and indexability.
Computed columns can be either deterministic or nondeterministic, while function-based indexes must be deterministic. "Deterministic" means that if the input values in an expression are the same, the return values must also be the same.
Computed columns can be materialized or not materialized. Columns that are materialized are preevaluated and stored in the table when base columns are inserted or updated. Any subsequent access to a materialized column does not require reevaluation; its preevaluated result is accessed.
Computed columns that are not materialized are called virtual columns with the value evaluated each time the column is accessed. A nondeterministic expression for a virtual column may result in different values for each access.
Materialized computed columns must be replicated as there is no method to determine if the expression is deterministic or nondeterministic.
A table-level replication definition for encrypted columns
must be provided, even if database-level replication or warm standby
is used.
