60af2f3cb2
Prototype implementation of format suggested/requested by @avikivity: Divides segments into disk-write-alignment sized pages, each tagged with segment ID + CRC of data content. When read, we both verify sector integrity (CRC) to detect corruption, as well as matching ID read with expected one. If the latter mismatches we have a prematurely terminated segment (read truncation), which, depending on whether the CL is written in batch or periodic mode, as well as explicit sync, can mean data loss. Note: all-zero pages are treated as kosher, both to align with newly allocated segments, as well as fully terminated (zero-page) ones. Note: This is a preview/RFC - the rest of the file format is not modified. At least parts of entry CRC could probably be removed, but I have not done so yet (needs some thinking). Note: Some slight abstraction breaks in impl. and probably less than maximal efficiency. v2: * Removed entry CRC:s in file format. * Added docs on format v3 * Added one more test for recycling-truncation v3: * Fixed typos in size calc and docs * Changed sect metadata order * Explicit iter type Closes scylladb/scylladb#15494 * github.com:scylladb/scylladb: commitlog_test: Add test for replaying large-ish mutation commitlog_test: Add additional test for segmnent truncation docs: Add docs on commitlog format 3 commitlog: Remove entry CRC from file format commitlog: Implement new format using CRC:ed sectors commitlog: Add iterator adaptor for doing buffer splitting into sub-page ranges fragmented_temporary_buffer: Add const iterator access to underlying buffers commitlog_replayer: differentiate between truncated file and corrupt 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.