Delete Always Wins Timestamp CDR
DELETE ALWAYS WINS is enabled through the field
ADDITIONAL_OPTIONS in both DBMS_GOLDENGATE_ADM
procedures ADD_AUTO_CDR() and ALTER_AUTO_CDR(). This
is again a delete conflict resolution method, which is not using latest timestamp
resolution, therefore, versioning is needed. Turning on DELETE ALWAYS
WINS automatically turns on versioning, which adds a new hidden column
KEYVER$$ (version number) of type timestamp. A new flag value is
also added to acdrflags_kqldtvc to indicate DELETE ALWAYS
WINS usage. This field is also added to the DELETE
TOMBSTONE table. The same versioning issues exist as the EARLIEST TIMESTAMP
resolution.
Example:
Key Version kv and Timestamp ts
Database 1: insert tab1 key1 kv1 ts1
Database 2: delete tab1 key1 kv1 ts1
Insertion to DELETE TOMBSTONE table key1 kv1
ts1
Database 1: insert tab1 key1 kv2 ts2
Without using the key version, the insert would be ignored, the delete
always wins. As the key version is used, you know that kv2 is not
the version of the row that was deleted and the insert succeeds.