Oracle GoldenGate

Oracle GoldenGate is a powerful tool for real-time data replication and integration across databases. This post covers essential GoldenGate concepts, architecture, components, and common interview questions to help DBAs prepare easily and confidently.

1. What is Oracle GoldenGate and why is it used?
Oracle GoldenGate is a software for real-time data replication and synchronization between databases. It’s used for high availability, disaster recovery, and data integration.

2. Explain the basic architecture of Oracle GoldenGate.
GoldenGate has Capture (Extract), Pump, and Replicat processes. Capture reads changes from source logs, Pump transfers data, and Replicat applies changes to the target.

3. What are the key components of GoldenGate?
Manager, Extract (Capture), Data Pump, Trail Files, and Replicat.

4. How does GoldenGate achieve real-time data replication?
By continuously reading database transaction logs and applying changes to the target database with minimal delay.

5. What is the difference between Capture, Pump, and Replicat processes?
Capture extracts changes from source logs; Pump moves data to the target; Replicat applies changes to the target database.

6. What types of replication does GoldenGate support?
One-way, bi-directional, and multi-master replication.

7. How do you configure GoldenGate for initial data load?
Use data pump or external tools to load initial data before starting replication.

8. What are trail files in GoldenGate?
Trail files store captured changes in a platform-independent format for transfer and application on the target.

9. How does GoldenGate handle data transformation during replication?
It supports built-in functions and parameter files to transform data on the fly.

10. What is the role of the Manager process?
Manages GoldenGate processes and monitors resources.

11. How do you monitor GoldenGate processes?
Using GGSCI commands, log files, and Oracle Enterprise Manager.

12. What are the typical challenges in GoldenGate replication?
Network latency, data conflicts, lagging replicat, and handling DDL changes.

13. How does GoldenGate ensure data consistency?
By capturing committed transactions from redo logs and applying them in order.

14. Can GoldenGate replicate between heterogeneous databases?
Yes, it supports replication across different database platforms like Oracle to SQL Server.

15. How is conflict detection and resolution handled?
Using built-in conflict detection parameters and user-defined conflict resolution logic.

16. What is integrated capture and how does it differ from classic capture?
Integrated capture uses Oracle LogMiner and is recommended for Oracle 11g and above for better performance and support.

17. How do you perform failover and recovery in GoldenGate?
By configuring Manager for automatic restart and handling trail files correctly.

18. What are Extract and Replicat parameters?
Parameters control how Extract and Replicat processes behave, like source tables, mapping, and filters.

19. How do you handle DDL replication with GoldenGate?
GoldenGate supports limited DDL replication using special parameters and scripts.

20. What is Oracle GoldenGate Veridata and why is it used?
Veridata is a tool to compare and verify data consistency between source and target databases.