e145e758eb
When we create a CDC generation and ring-delay is non-zero, the timestamp of the new generation is in the future. Hence, we can have multiple generations that can be written to. However, if we add a new node to the cluster with the Raft-based topology, it receives only the last committed generation. So, this node will be rejecting writes considered correct by the other nodes until the last committed generation starts operating. In scylladb/scylladb#17134, we have allowed sending writes to the previous CDC generations. So, the situation became even more complicated. We need to adjust the Raft-based topology to ensure all required generations are loaded into memory and their data isn't cleared too early. This patch is the first step of the adjustment. We replace `current_cdc_generation_{uuid, timestamp}` with the set containing IDs of all committed generations - `committed_cdc_generations`. This set is sorted by timestamps, just like `unpublished_cdc_generations`. This patch is mostly refactoring. The last generation in `committed_cdc_generations` is the equivalent of the previous `current_cdc_generation_{uuid, timestamp}`. The other generations are irrelevant for now. They will be used in the following patches. After introducing `committed_cdc_generations`, a newly committed generation is also unpublished (it was current and unpublished before the patch). We introduce `add_new_committed_cdc_generation`, which updates both sets of generations so that we don't have to call `add_committed_cdc_generation` and `add_unpublished_cdc_generation` together. It's easy to forget that both of them are necessary. Before this patch, there was no call to `add_unpublished_cdc_generation` in `topology_coordinator::build_coordinator_state`. It was a bug reported in scylladb/scylladb#17288. This patch fixes it. This patch also removes "the current generation" notion from the Raft-based topology. For the Raft-based topology, the current generation was the last committed generation. However, for the `cdc::metadata`, it was the generation operating now. These two generations could be different, which was confusing. For the `cdc::metadata`, the current generation is relevant as it is handled differently, but for the Raft-based topology, it isn't. Therefore, we change only the Raft-based topology. The generation called "current" is called "the last committed" from now.
ScyllaDB Documentation
This repository contains the source files for ScyllaDB Open Source documentation.
- The
devfolder contains developer-oriented documentation related to the ScyllaDB code base. It is not published and is only available via GitHub. - All other folders and files contain user-oriented documentation related to ScyllaDB Open Source and are sources for docs.scylladb.com.
To report a documentation bug or suggest an improvement, open an issue in GitHub issues for this project.
To contribute to the documentation, open a GitHub pull request.
Key Guidelines for Contributors
- Follow the ScyllaDB Style Guide.
- The user documentation is written in reStructuredText (RST) - a plaintext markup language similar to Markdown. If you're not familiar with RST, see ScyllaDB RST Examples.
- The developer documentation is written in Markdown. See Basic Markdown Syntax for reference.
Creating Knowledge Base Articles
The kb/ directory holds source files for knowledge base articles in the Knowledge Base section of the ScyllaDB documentation.
The kb/kb_common subdirectory contains a template for knowledge base articles to help you create new articles.
To create a new knowledge base article (KB):
- Copy the
kb-article-template.rstfile from/kb/kb_commonto/kband rename it with a unique name. - Open the new file and fill in the required information.
- Remove what is not needed.
- Run
make previewto build the docs and preview them locally. - Send a PR with "KB" in its title.
Building User Documentation
Prerequisites
- Python 3. Check your version with
$ python --version. - poetry 1.12 or later
- make
Mac OS X
You must have a working Homebrew in order to install the needed tools.
You also need the standard utility make.
Check if you have these two items with the following commands:
brew help
make -h
Linux Distributions
Building the user docs should work out of the box on most Linux distributions.
Windows
Use "Bash on Ubuntu on Windows" for the same tools and capabilities as on Linux distributions.
Building the Docs
- Run
make previewto build the documentation. - Preview the built documentation locally at http://127.0.0.1:5500/.
Cleanup
You can clean up all the build products and auto-installed Python stuff with:
make pristine
Information for Contributors
If you are interested in contributing to Scylla docs, please read the Scylla open source page at http://www.scylladb.com/opensource/ and complete a Scylla contributor agreement if needed. We can only accept documentation pull requests if we have a contributor agreement on file for you.
Third-party Documentation
-
Do any copying as a separate commit. Always commit an unmodified version first and then do any editing in a separate commit.
-
We already have a copy of the Apache license in our tree, so you do not need to commit a copy of the license.
-
Include the copyright header from the source file in the edited version. If you are copying an Apache Cassandra document with no copyright header, use:
This document includes material from Apache Cassandra.
Apache Cassandra is Copyright 2009-2014 The Apache Software Foundation.