c75375b148
When streaming SSTables by tablet range, the original implementation of tablet_sstable_streamer::stream may break out of the loop too early when encountering a non-overlaping SSTable. As a result, subsequent SSTables that should be classified as partially contained are skipped entirely. Tablet range: [4, 5] SSTable ranges: [0,5] [0, 3] <--- is considered exhausted, and causes skip to next tablet [2, 5] <--- is missed for range [4, 5] The loop uses if (!overlaps) break; semantics, which conflated “no overlap” with “done scanning.” This caused premature termination when an SSTable did not overlapped but the following one did. Correct logic should be: before(sst_last) → skip and continue. after(sst_first) → break (no further SSTables can overlap). Otherwise → `contains` to classify as full or partial. Missing SSTables in streaming and potential data loss or incomplete streaming in repair/streaming operations. 1. Correct the loop termination logic that previously caused certain SSTables to be prematurely excluded, resulting in lost mutations. This change ensures all relevant SSTables are properly streamed and their mutations preserved. 2. Refactor the loop to use before() and after() checks explicitly, and only break when the SSTable is entirely after the tablet range 3. Add pytest to cover this case, full streaming flow by means of `restore` 4. Add boost tests to test the new refactored function This data corruption fix should be ported back to 2024.2, 2025.1, 2025.2, 2025.3 and 2025.4 Fixes: https://github.com/scylladb/scylladb/issues/26979 - (cherry picked from commit656ce27e7f) - (cherry picked from commitdedc8bdf71) Parent PR: #26980 Closes scylladb/scylladb#27156 * github.com:scylladb/scylladb: streaming: fix loop break condition in tablet_sstable_streamer::stream streaming: add pytest case to reproduce mutation loss issue
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.