fbcf77d134
A recent commit370707b111(re)introduced a timeout for every group0 Raft operation. This timeout was set to 60 seconds, which, paraphrasing Bill Gates, "ought to be enough for anybody". However, one of the things we do as a group0 operation is schema changes, and we already noticed a few years ago, see commit0b2cf21932, that in some extremely overloaded test machines where tests run hundreds of times (!) slower than usual, a single big schema operation - such as Alternator's DeleteTable deleting a table and multiple of its CDC or view tables - sometimes takes more than 60 seconds. The above fix changed the client's timeout to wait for 300 seconds instead of 60 seconds, but now we also need to increase our Raft timeout, or the server can time out. We've seen this happening recently making some tests flaky in CI (issue #23543). So let's make this timeout configurable, as a new configuration option group0_raft_op_timeout_in_ms. This option defaults to 60000 (i.e, 60 seconds), the same as the existing default. The test framework overrides this default with a a higher 300 second timeout, matching the client-side timeout. Before this patch, this timeout was already configurable in a strange way, using injections. But this was a misstep: We already have more than a dozen timeouts configurable through the normal configration, and this one should have been configured in the same way. There is nothing "holy" about the default of 60 seconds we chose, and who knows maybe in the future we might need to tweek it in the field, just like we made the other timeouts tweakable. Injections cannot be used in release mode, but configuration options can. Fixes #23543 Signed-off-by: Nadav Har'El <nyh@scylladb.com> Closes scylladb/scylladb#23717
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.