9116fc635e
`tablet_storage_group_manager::all_storage_groups_split()` calls `set_split_mode()` for each of its storage groups to create split ready compaction groups. It does this by iterating through storage groups using `std::ranges::all_of()` which is not guaranteed to iterate through the entire range, and will stop iterating on the first occurrence of the predicate (`set_split_mode()`) returning false. `set_split_mode()` creates the split compaction groups and returns false if the storage group's main compaction group or merging groups are not empty. This means that in cases where the tablet storage group manager has non-empty storage groups, we could have a situation where split compaction groups are not created for all storage groups. The missing split compaction groups are later created in `tablet_storage_group_manager::split_all_storage_groups()` which also calls `set_split_mode()`, and that is the reason why split completes successfully. The problem is that `tablet_storage_group_manager::all_storage_groups_split()` runs under a group0 guard, but `tablet_storage_group_manager::split_all_storage_groups()` does not. This can cause problems with operations which should exclude with compaction group creation. i.e. DROP TABLE/DROP KEYSPACE Fixes #22431 This is a bugfix and should be back ported to versions with tablets: 6.1 6.2 and 2025.1 - (cherry picked from commit24e8d2a55c) - (cherry picked from commit8bff7786a8) Parent PR: #22330 Closes scylladb/scylladb#22560 * github.com:scylladb/scylladb: test: add reproducer and test for fix to split ready CG creation table: run set_split_mode() on all storage groups during all_storage_groups_split()
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++23 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain, This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its API - CQL. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The community forum and Slack channel are for users to discuss configuration, management, and operations of the ScyllaDB open source.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.