Replication (computing): Difference between revisions

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== {{Anchor|DATABASE}}Database replication ==

[[Database]] replication can be used on many [[database management system]]s (DBMS), usually with a [[master/slave (technology)| primary/replica]] relationship between the original and the copies. The masterprimary logs the updates, which then ripple through to the replicas. Each replica outputs a message stating that it has received the update successfully, thus allowing the sending of subsequent updates.

In [[multi-master replication]], updates can be submitted to any database node, and then ripple through to other servers. This is often desired but introduces substantially increased costs and complexity which may make it impractical in some situations. The most common challenge that exists in multi-master replication is transactional conflict prevention or [[conflict resolution|resolution]]. Most synchronous (or eager) replication solutions perform conflict prevention, while asynchronous (or lazy) solutions have to perform conflict resolution. For instance, if the same record is changed on two nodes simultaneously, an eager replication system would detect the conflict before confirming the commit and abort one of the transactions. A [[lazy replication]] system would allow both [[database transaction|transactions]] to commit and run a conflict resolution during re-synchronization.<ref>{{cite book