Both ADG and OGG are HA solution of Oracle for business，we can duplication database data to others hosts by using those two technology. The following table lists the difference between ADG and OGG
| ADG | OGG | |
|---|---|---|
| Overview | Full Backup based on Online Log or Archiving Log files | Partial Backup or Full Backup based on the difference of Online Log files |
| Stability | High | Lower than ADG |
| Maintenance | Easy based on backup and restoring | Professional and complex based on command， support DML and DDL backup and restoring |
| Objects Supporting | All Objects of Oracle Database | Not all Objects by default but DBAs are able to enable and manage them to make sure OGG support them |
| Backup Host Serviceability |
There are two status for ADG , restoring or read-only. If the backup database in read-only status, the backup database is not available |
All backup databases are online database, OGG backup databases are able to provide computing service for real-time selection or reporting transaction |
| Take-Over | We need manually take online /open backup database in order to take over database service while main host down | Instantly take over database service when main host down |
| Duplication Approach | Backup and restoring, can not realize synchronous duplication | Close to synchronous duplication , provide seconds level of GB data capture and transfer , Asynchronous replication |
| Resource Occupancy | ADG creates LGWR and ARCN two processes to process the duplication service with low resources occupancy | The peak time has high resources occupancy due to real time catching the difference data in online log files and convert those data into GGS format |
| Data Exchange | Not Support, The Oracle database only and requires same Operation System | Support data exchange between different system(AIX, Linux, Windows etc.) and databases(Oracle , Mysql , DB2 etc.) |
| Transfer | Use Oracle Net tunnel to transfer the log files | Use TCP/TP protocol to transfer the GGS queue data |
| Compression ratio | 2:1 to 3:1 | near to 9:1 |
| Topology | 1:n | 1:n or n:1 or two-way duplication |