Rebalancing
Explore how rebalancing works in distributed databases to maintain uniform data and workload distribution across host instances. Understand fixed and dynamic partitioning techniques, their advantages, and challenges. This lesson helps you grasp how databases handle host instance changes and data scaling with minimal disruption.
Introduction
Rebalancing in a distributed system is data movement between multiple host instances. In the context of database partitioning, rebalancing means the movement of partitions between multiple host instances.
These are scenarios where a distributed database requires rebalancing:
If an existing host instance crashes, the database must migrate partitions from the existing host to other hosts.
If a new host instance joins the cluster, the database must reassign partitions to the new host from the existing ones for uniform distribution.
Scaling up host instances by adding more CPU, memory, etc., requires redistributing partitions between the hosts.
The database must redistribute partitions between host instances as the query throughput and dataset increase over time.
Prerequisites
There are certain prerequisites for rebalancing partitions in a distributed database:
After the rebalance operation, the data storage and read/write distribution on the partitions should be uniform between the host instances.
During the rebalance process, the ...