de81388edb
Refs #18161 Yet another approach to dealing with large commitlog submissions. We handle oversize single mutation by adding yet another entry typo: fragmented. In this case we only add a fragment (aha) of the data that needs storing into each entry, along with metadata to correlate and reconstruct the full entry on replay. Because these fragmented entries are spread over N segments, we also need to add references from the first segment in a chain to the subsequent ones. These are released once we clear the relevant cf_id count in the base. * This approach has the downside that due to how serialization etc works w.r.t. mutations, we need to create an intermediate buffer to hold the full serialized target entry. This is then incrementally written into entries of < max_mutation_size, successively requesting more segments. On replay, when encountering a fragment chain, the fragment is added to a "state", i.e. a mapping of currently processing frag chains. Once we've found all fragments and concatenated the buffers into a single fragmented one, we can issue a replay callback as usual. Note that a replay caller will need to create and provide such a state object. Old signature replay function remains for tests and such. This approach bumps the file format (docs to come). To ensure "atomicity" we both force synchronization, and should the whole op fail, we restore segment state (rewinding), thus discarding data all we wrote. Closes scylladb/scylladb#19472 * github.com:scylladb/scylladb: commitlog/database: Make some commitlog options updatable + add feature listener features/config: Add feature for fragmented commitlog entries docs: Add entry on commitlog file format v4 commitlog_test: Add more oversized cases commitlog_replayer: Replay segments in order created commitlog_replayer: Use replay state to support fragmented entries commitlog_replayer: coroutinize partly commitlog: Handle oversized entries
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.