Monimestarijärjestelmät

Monimestarijärjestelmät, sometimes translated as "multiple master systems" or "multi-master systems", refers to a type of distributed database architecture where multiple database servers can accept write operations independently. Unlike traditional master-slave configurations where only one server handles writes and others replicate the data, in a multi-master setup, any of the designated master nodes can be updated. This allows for greater availability and reduced latency, especially in geographically distributed applications.

When a write operation occurs on one master, the changes are then propagated to the other master nodes. This replication process can happen synchronously or asynchronously, each with its own trade-offs regarding consistency and performance. Synchronous replication ensures that all masters have the same data before acknowledging a write, providing strong consistency but potentially increasing latency. Asynchronous replication acknowledges the write sooner, improving performance but introducing a window where data might be temporarily inconsistent across nodes.

A significant challenge in multi-master systems is conflict resolution. Since multiple nodes can modify the same data concurrently, conflicts can arise. These conflicts must be detected and resolved to maintain data integrity. Various strategies exist, such as last-writer-wins, first-writer-wins, or more complex application-specific logic. The choice of conflict resolution mechanism is crucial for the overall reliability and correctness of the system.

Multi-master architectures are often employed in scenarios requiring high availability and performance for read and write operations across multiple locations. Examples include global e-commerce platforms, content management systems, and applications where downtime is unacceptable. However, their complexity in management, replication, and conflict resolution means they are not a universal solution and require careful consideration of the application's specific needs.