How Oracle GoldenGate Determines the Kind of Row Identifier to Use

Unless a KEYCOLS clause is used in the TABLE or MAP statement, Oracle GoldenGate selects a row identifier to use in the following order of priority:

Primary key (required for tables of a Standard Edition instance).
First unique key alphanumerically that does not contain a timestamp or non-materialized computed column.
If neither of these key types exist , Oracle GoldenGate constructs a pseudokey of all columns that the database allows to be used in a unique key, excluding those that are not supported by Oracle GoldenGate in a key or those that are excluded from the Oracle GoldenGate configuration.

Note:

If there are types of keys on a table or if there are no keys at all on a table, Oracle GoldenGate logs a message to the report file. Constructing a key from all of the columns impedes the performance of Oracle GoldenGate on the source system. On the target, this key causes Replicat to use a larger, less efficient WHERE clause.