The replication process typically is implemented by the database system. No application code required. ✅ (Many cases that is what we want)
Although.. in some circumstances replication can been needed to perform:
- Replication of a subset of data
- Replication to one kind of database to another
- Conflict resolution
You may ay require moving replication to the application layer such as toolset:
- Oracle GoldenGate
- This can make data changes available to an application by reading the database log 🕵️♂️
Alternative, features that are available in many RDBMS:
- Triggers
- Stored procedures
What are Triggers?
These will let you register custom application code that is automatically executed when a data change (write transaction) occurs in a database system.
- A trigger has the opportunity to log this change into a separate table
- That can be read from external process
- 🤔 That external process can then apply the necessary application logic and replicate the data change to another system
- 👉 Postgres from Bucardo works like this for example
Cons of trigger based replication
- 👎 Typically has greater overheads than other applications methods
- 👎 More prone to bugs and limitation than built in replication
📚 Further Reading & Related Topics
If you’re exploring replication strategies in distributed systems, these related articles will provide additional insights into data consistency and conflict resolution:
• Distributed Data-Intensive Systems: Logical Log Replication – Learn how logical logs help maintain consistency in distributed databases and complement trigger-based replication strategies.
• Resolving Write Conflicts in Distributed Data-Intensive Systems – Understand different techniques for managing conflicts that arise in replicated environments, ensuring data integrity across distributed nodes.
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