Multi-master replication for distributed data synchronization
Core Idea: CouchDB's bidirectional synchronization enables data to flow between multiple devices and servers, maintaining consistency across distributed systems while handling conflicts gracefully.
Key Elements
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Synchronization Architecture:
- Multi-master replication between instances
- Change-based replication protocol
- HTTP/REST-based sync mechanism
- Incremental updates for efficiency
- Revision tracking for conflict detection
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Sync Workflow:
- Local to cloud: Changes on device sent to server
- Cloud to local: Changes from server pulled to device
- Automatic sync when network available
- Manual sync triggers (pull/push operations)
- Background sync processes
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Conflict Resolution:
- Automatic detection of document conflicts
- Conflict markers in document metadata
- Application-defined resolution strategies
- User interface for manual conflict resolution
- Preservation of conflicted versions
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Implementation Considerations:
- Revision tracking (_rev field in documents)
- Document history maintained until compaction
- Eventual consistency model
- Network interruption handling
- Resumable sync operations
Practical Applications
- Synchronizing data across multiple devices
- Offline-first application architecture
- Collaborative editing applications
- Point-of-sale systems with multiple terminals
- Field service applications with intermittent connectivity
Design Patterns
- "Accountants don't use erasers" pattern for append-only records
- Using timestamps for ordering changes
- Conflict-free data structures for specific use cases
- Separate documents for frequently changing data
Connections
- Related Concepts: CouchDB (implementation platform), PouchDB (client implementation), Conflict Resolution (key capability)
- Broader Context: Eventual Consistency (consistency model), Distributed Database Systems (architectural pattern)
- Applications: Offline-First Applications (implementation pattern), Inkdrop (real-world example)
- Components: CouchDB Replication Protocol (technical standard)
References
- CouchDB documentation on replication
- PouchDB conflict resolution guide
- Implementation experiences from Inkdrop development
#synchronization #replication #couchdb #offline-first #distributed-systems
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