20fe1e6f68
When finalizing a tablet split, all data must have been moved into split-ready compaction groups before the storage groups can be remapped to the new tablet count. If split-unready groups still hold data at that point, handle_tablet_split_completion() calls on_internal_error(), which previously only reported the tablet and table IDs — giving no insight into why the split-unready groups were not empty. Add fmt::formatter specializations for compaction_group and storage_group so the full state of the offending storage_group is included in the error message. The storage_group formatter emits: main=<cg>, merging=[<cg>...], split_ready=[<cg>...] Each compaction_group formatter emits: [sstables=[<sstable_desc>...], memtable_empty=<bool>, sstable_add_gate=<count>] where sstable_desc includes filename, origin, identifier and originating host, memtable_empty reflects whether all memtables have been flushed, and sstable_add_gate count reveals whether an in-flight sstable add is holding data in the group. Supporting changes: - compaction_group: add memtable_empty() const noexcept (delegates to memtable_list::empty()) and a const overload of sstable_add_gate() so both are accessible from a const compaction_group reference inside the formatter. - Promote sstable_desc from a local lambda in compaction_group_for_sstable to a static free function so it is reusable by the formatter. Refs https://scylladb.atlassian.net/browse/SCYLLADB-1019. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com> Closes scylladb/scylladb#29178
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 ScyllaDB.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.