Scylla has released version 6.0 of its NoSQL database ScyllaDB. The open source database, designed for high performance from the beginning, is learning a new replication architecture with the current release.
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This release also brings improvements to strictly consistent topology updates and consistent access control updates.
Replication with Google instead of Cassandra architecture
ScyllaDB 6.0 relies on tablets for data distribution in the cluster. Google first came up with the concept of distributed database system BigTable introduced and uses it in its successor Spanner. Tablets consist of multiple rows of tables. Nodes of BigTable do not contain data, but only pointers to tablets.
The database partitions tables into tablets, which it distributes across multiple nodes in the cluster.
(Picture: rock,
Flexible Delivery
The load balancer distributes the data dynamically and can resize it if needed, i.e. split large tablets or merge smaller ones. The load balancer distributes the split tablets to different nodes independently.
In this way, the system can react flexibly to changes in requests, content, or available nodes.
When a new node is added, it takes over tablets from busy nodes.
(Image: Scylla)
Tablet architecture is more flexible than concept Replication with Virtual Nodeswhich inherited ScyllaDB from Cassandra and was used until version 5.4.
The current version of ScyllaDB uses the tablet architecture by default. If you want to disable it because, among other things, the architecture does not allow lightweight transactions, you must set the corresponding keyspace with the flag tablets = { 'enabled': false } Make it.
Stability in topology
The second major innovation is strictly consistent topology updates. Scylla relies on the Raft algorithm – it was here Database based on the Cassandra model in early 2023 and adopted its Paxos algorithm.
ScyllaDB 6.0 enables raft-based, strictly consistent topology updates for new clusters by default. A post in the documentation statesHow to manually convert an existing cluster.
In addition to topology updates, the database now also guarantees strictly consistent role-based access control (RBAC) authentication updates and consistent service levels.
Cassandra as a role model, taking performance into account
The team behind ScyllaDB first presented the NoSQL database at the Cassandra Summit in 2015. The database was designed from the start to be compatible with Cassandra, but should be significantly more performant. Since it is written in C++, while Cassandra relies on Java, it does not require a Java Virtual Machine (JVM) with an associated garbage collector.
ScyllaDB is also used for performance reasons A shared nothing architectureIn which each data segment is given fixed resources (CPU, RAM, network and persistent memory) to prevent delays and deadlocks while sharing data between resources.
Scylla spoke out in late 2018 In the blog The release of version 3.0 proved to be an important milestone as the company had “surpassed feature parity with Apache Cassandra.” The database is now going its own way in some areas, such as with the new Tablets instead of VNodes or with Raft instead of Paxos.
Other innovations in ScyllaDB 6.0 such as node tool for managing nodes from the command line can be found on the Scylla blog,
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