Apache Cassandra places copies of the same data on multiple nodes to ensure fault tolerance and no single point of failure. This operation is called replication and the data copies are called replicas. Replication is done on a row basis.

1. Replication Strategy

Replication is defined by Replication strategy when creating a keyspace. One [...]

Compaction in Apache Cassandra refers to the operation of merging multiple SSTables into a single new one. It mainly deals with the following. Merge keys Combine columns Discard tombstones

Compaction is done for two purposes. bound the number of SSTables to consult on reads. Cassandra’s write model allows multiple versions of a row exists [...]

This is a follow up post on previous post How Apache Cassandra Read Works.

0. Partitioners and Snitches

Partitioners and snitches affects Cassandra reads. We briefly describe them first.

Partitioners

Partitioner allows us to specify how row keys should be sorted, which affects how data is distributed across Cassandra nodes. At read, it [...]

Apache Cassandra is known to have good write performance, mainly because all writes are sequential and there’s no reading and seeking before writes. This post covers how write works on Apache Cassandra.

1. The Write Process

Below is a diagram that illustrates Cassandra write process.

As shown in the diagram above, a client sends a [...]