[RELEASE] ScyllaDB 2025.1

Release Notes
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The ScyllaDB team is pleased to announce the release of ScyllaDB 2025.1.0 LTS, a production-ready ScyllaDB Enterprise Long Term Support Major Release.

With the 2025.1 LTS release, ScyllaDB Enterprise 2023.1 become End Of Life (EOL).

More information on ScyllaDB Long Term Support (LTS) policy is available here.

2025.1 is the first Source Available License release, replacing both ScyllaDB Open Source and Enterprise releases. The release accumulates all the improvements from Enterprise releases (up to 2024.2) and Open Source Releases (up to 6.2).

ScyllaDB 2025.1 focuses on making Tablets, first introduced in 2024.2, production-ready and enabled by default. Among others ScyllaDB 2025.1 improves performance, scaling speed, support for mix clusters (using different instance types), bug fixes and much more.

ScyllaDB, with Tablets, and Mix instance Size support is the base for the upcoming ScyllaDB X Cloud, a new and improved Scylla Cloud offering which supports fast boot, fast scaling (out and in) and an upper limit of 90% storage utilization, compared to 70% today.

Relevant links

ScyllaDB Enterprise customers are encouraged to upgrade to ScyllaDB 2025.1, and are welcome to contact our Support Team with questions.

For best use of ScyllaDB 2025.1, use ScyllaDB Manager 3.5 and later, and ScyllaDB Monitoring Stack 4.9 and later.

Tablets

In this release, ScyllaDB makes tablets the default for new Keyspaces. Tablets are a new data distribution algorithm as a better alternative to the legacy vNodes approach inherited from Apache Cassandra.

While the vNodes approach statically distributes all tables across all nodes and shards based on the token ring, the Tablets approach dynamically distributes each table to a subset of nodes and shards based on its size. In the future, distribution will use CPU, OPS, and other information to further optimize the distribution.

In particular, Tablets provide the following:

  • Faster scaling and topology changes. New nodes can start serving reads and writes as soon as the first Tablet is migrated. Together with Strongly Consistent Topology Updates, this also allows users to add multiple nodes simultaneously.
  • Automatic support for mixed clusters with different core counts.

Note that you can run a cluster with some of the Keyspaces with Tablets disabled, and some with tablets enabled for as long as you wish. The scaling improvement will be partial, and limited to Keyspaces with Tablets enabled.

vNodes will continue to be supported for existing Keyspaces as well as new Keyspaces using the tablets = { 'enabled': false } option.

Initial tablet number

By default, the number of tablets is dynamically set by the database, and there is no need to set it.

However, if you know in advance the expected size of the data, you can speed up initial data ingestion, by setting the initial tablet number to: expected size (before replication) divided by 5GB.

tablets = { 'initial': 2048};

Follow up patch release will deprecate this parameter for more flexible per table tablet options .

Tablet Merge

The goal of Tablet Merge is to reduce the tablet count for a shrinking table. Similar to how split increases the count while the table is growing. The load balancer decision to merge is implemented today (came with infrastructure introduced for split), but it wasn’t handled until now.

The topology coordinator will now detect tables that have shrunk, and merge adjacent tablets in order to meet the average tablet replica size goal. #18181

Tablets Limitations

Tablets Keyspaces are not yet enabled for the following features:

  • Materialized view
  • Secondary Indexes
  • CDC
  • LWT
  • Counters
  • Alternator (Amazon DynamoDB API) - partially; see below.

Alternator support Tablets with the following:

  • with Alternator Write Isolation of with forbid or unsafe, which does not use LWT (not always or only_rmw_uses_lwt)
  • Using initial_tablets tag.
  • Avoiding TTL

Read more about Tablets here.

Note: you can not ALTER an existing Keyspace to switch between Tablets and vNode based table and back. We will remove these restrictions in upcoming releases.

More improvments here: [RELEASE] ScyllaDB 2025.1 - part 2

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