Automatic Conflict Detection and Resolution (ACDR) was introduced in Oracle Database 12c Release 2 (and Oracle GoldenGate 12.3.0.1) to automate the conflict detection and resolution configuration in active-active Oracle GoldenGate replication setups.

In Oracle Database 21c, Oracle enhanced ACDR to support earliest timestamp based resolution and site priority based resolution.

In Oracle Database 23c, Oracle is enhancing ACDR with the following:

• Simplified methods to manage & maintain AUTO_CDR configured tables

• By default, Auto-CDR internal columns are marked as UNUSED when calling DELETE_AUTO_CDR Auto-CDR

• Removing UNUSED columns in a maintenance window at a later time:
  • ALTER TABLE DROP … UNUSED COLUMN
  • DBMS_REDEFINITION

• Useful for large tables where the operation is resource intensive

• To drop Auto-CDR internal columns immediately with DELETE_AUTO_CDR:
  • Use REMOVE_HIDDEN_COLUMNS  flag of additional_options parameter from ADD_AUTO_CDR/ALTER_AUTO_CDR call

• Support for DBMS_REDEFINITION on ACDR related tables (Edition Based Redefinition)