In general, Delphix recommends enabling Block Change Tracking (BCT) on a primary or standby source database. See Physical Standby Database Support Matrix in this topic for restrictions on enabling BCT on a standby database.
BCT is available from Oracle release 184.108.40.206 onward for physical standby databases only if they are licensed for the Active Data Guard option.
Enabling BCT on a physical standby database without these patches is not recommended because of serious performance and stability issues.
BCT on a primary database has been stable since Oracle version 10.2.0.5.