b13ab90448
When executing reversed queries, a native revered format shall be used. Therefore, the table schema and the clustering key bounds are reversed before a partition slice and a read command are constructed. It is, however, possible to run a reversed query passing a table schema but only when there are no restrictions on the clustering keys. In this particular situation, the query returns correct results. Since the current alternator tests in test.py do not imply any restrictions, this situation was not caught during development of https://github.com/scylladb/scylladb/pull/18864. Hence, additional tests are provided that add clustering keys restrictions when executing reversed queries to capture such errors earlier than in dtests. Additional manual tests were performed to test a mixed-node cluster (with alternator API enabled in Scylla on each node): 1. 2-node cluster with one node upgraded: reverse read queries performed on an old node 2. 2-node cluster with one node upgraded: reverse read queries performed on a new node 3. 2-node cluster with one node upgraded and all its sstable files deleted to trigger repair: reverse read queries performed on an old node 4. 2-node cluster with one node upgraded and all its sstable files deleted to trigger repair: reverse read queries performed on a new node All reverse read queries above consists of: - single-partition reverse reads with no clustering key restrictions, with single column restrictions and multi column restrictions both with and without paging turned on The exact same tests were also performed on a fully upgraded cluster. Fixes https://github.com/scylladb/scylladb/issues/20191 No backport is required as this is a complementary patch for the series https://github.com/scylladb/scylladb/pull/18864 that did not require backporting. Closes scylladb/scylladb#20205 * github.com:scylladb/scylladb: test_query.py: Test reverse queries with clustering key bounds alternator::do_query Add additional trace log alternator::do_query: Use native reversed format alternator::do_query Rename schema with table_schema
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.