Primærdatabases

Primærdatabase refers to the main or principal database in a system. It is the authoritative source of data, holding the most up-to-date and complete information. In many software architectures, especially those involving replication or distributed systems, a primary database is designated to handle all write operations. This ensures data consistency and integrity, as all changes are first applied to this central point.

Other databases in the system, often referred to as replicas or secondary databases, then synchronize with the primary database. These replicas are typically used for read operations to distribute the load and improve query performance. If the primary database fails, a promotion process can occur where a replica is designated as the new primary to maintain system availability.

The concept of a primary database is fundamental to ensuring a single source of truth for an application's data. It simplifies data management and reduces the complexity of handling concurrent writes across multiple database instances. While the term is general, its specific implementation can vary depending on the database technology and system design. For instance, in a master-slave replication setup, the master is the primary database. In a multi-master setup, all masters can be considered primary for their respective write operations, though a specific system might still designate one as the ultimate authority.