cdae15ced9
When a node that is permanently down is replaced, it is marked as "left" but it still can be a replica of some tablets. We also don't keep IPs of nodes that have left and the `node` structure for such node returns an empty IP (all zeros) as the address. This interacts badly with the view update logic. The base replica paired with the left node might decide to generate a view update. Because storage proxy still uses IPs and not host IDs, it needs to obtain the view replica's IP and tell the storage proxy to write a view update to that node - so, it chooses 0.0.0.0. Apparently, storage proxy decides to write a hint towards this address - hinted handoff on the other hand operates on host IDs and not IPs, so it attempts to translate the IP back, which triggers an assertion as there is no replica with IP 0.0.0.0. As a quick workaround for this issue just drop view updates towards nodes which seem to have IPs that are all zeros. It would be more proper to keep the view updates as hints and replay them later to the new paired replica, but achieving this right now would require much more significant changes. For now, fixing a crash is more important than keeping views consistent with base replicas. In addition to the fix, this PR also includes a regression test heavily based on the test that @kbr-scylla prepared during his investigation of the issue. Fixes: scylladb/scylladb#19439 This issue can cause multiple nodes to crash at once and the fix is quite small, so I think this justifies backporting it to all affected versions. 6.0 and 6.1 are affected. No need to backport to 5.4 as this issue only happens with tablets, and tablets are experimental there. (cherry picked from commit6af7882c59) (cherry picked from commit5ec8c06561) Refs #19765 Closes scylladb/scylladb#19896 * github.com:scylladb/scylladb: test: regression test for MV crash with tablets during decommission db/view: drop view updates to replaced node marked as left
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++20 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 APIs - CQL and Thrift. 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.