3ffe93b6ae
The main purpose of this change is to enhance the restore from object storage usage. Currently, restore uses the load-and-stream facility. When triggered, the restoring task opens the provided list of sstables directory from the remote bucket and then feeds the list of sstables to load_and_stream() method. The method, in turn, iterates over this list, reads mutations and for each mutation decides where to send one by checking the replication map (it's pretty much the same for both vnodes and tablets, but for tablets that are "fully contained" by a range there's the plan to stream faster). As described above, restore is governed by a single node and this single node reads all sstables from the object store, which can be very slow. This PR allows speeding things up. For that, the load-and-stream code is equipped with the "scope" filter which limits where mutations can be streamed to. There are four options for that -- all, dc, rack and node. The "all" is how things work currently, "dc" and "rack" filter out target nodes that don't belong to this node's dc/rack respectively. The "node" scope only streams mutations to local node. With the "node" scope it's possible to make all nodes in the cluster load mutations that belong to them in parallel, without re-sending them to peers. The last patch in this PR is the test that shows how it can be possible. Closes scylladb/scylladb#21169 * github.com:scylladb/scylladb: test: Add scope-streaming test (for restore from backup) api: New "scope" API param to load-and-stream calls sstables_loader: Propagate scope from API down sstables_loader: Filter tablets based on scope streamer: Disable scoped streaming of primary replica only sstables_loader: Introduce streaming scope sstables_loader: Wrap get_endpoints()
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.