Replication
On this page
The replication process forms an essential part of a disaster recovery (DR) plan.
SingleStore replicates data in the following situations.
-
When you run your cluster in high availability, redundancy-2 mode, SingleStore replicates data from master to replica partitions in the same cluster.
-
When you use the REPLICATE DATABASE command, SingleStore replicates data across clusters.
Synchronous Replication Debugging Flow
The diagram below shows what happens when an async alert is raised at the partition level.
![](https://images.contentstack.io/v3/assets/bltac01ee6daa3a1e14/blteb7fb58ebf2f65de/66db60eee81d782eb466e254/Sync_Replication_Debug_Flow-WOlxXZ.png?width=850&disable=upscale&auto=webp)
High availability, Redundancy-2 mode
With high availability redundancy-2 replication, you can specify, using the CREATE DATABASE, RESTORE DATABASE and ALTER DATABASE commands, whether replication from primary to replica partitions is synchronous or asynchronous.
Synchronous replication is usually no more than ten to twenty percent slower than asynchronous replication.
If a database is using synchronous replication and its replica partition fails to respond within five seconds, the replica partition switches to asynchronous replication; this allows the replica partition to not block the current and future replication transactions.
-
The replica partition becomes responsive.
-
The primary partition becomes responsive, if it was previously unresponsive.
When the replica partition resumes failover, it switches to synchronous replication.
REPLICATE DATABASE
When you use the REPLICATE DATABASE command, you can only replicate asynchronously.
Last modified: September 8, 2022