59ec93b86b
There are several reasons we want to do that. One is that it will give us more flexibility in distributing the load. We can subdivide tablets at any token, and achieve more evenly-sized tablets. In particular, we can isolate large partitions into separate tablets. We can also split and merge incrementally individual tablets. Currently, we do it for the whole table or nothing, which makes splits and merges take longer and cause wide swings of the count. This is not implemented in this PR yet, we still split/merge the whole table. Another reason is vnode to tablets migration. We now could construct a tablet map which matches exactly the vnode boundaries, so migration can happen transparently from CQL-coordinator point of view. Tablet count is still a power-of-two by default for newly created tables. It may be different if tablet map is created by non-standard means, or if per-table tablet option "pow2_count" is set to "false". build/release/scylla perf-tablets: Memory footprint for 131k tablets increased from 56 MiB to 58.1 MiB (+3.5%) Before: ``` Generating tablet metadata Total tablet count: 131072 Size of tablet_metadata in memory: 57456 KiB Copied in 0.014346 [ms] Cleared in 0.002698 [ms] Saved in 1234.685303 [ms] Read in 445.577881 [ms] Read mutations in 299.596313 [ms] 128 mutations Read required hosts in 247.482742 [ms] Size of canonical mutations: 33.945053 [MiB] Disk space used by system.tablets: 1.456761 [MiB] Tablet metadata reload: full 407.69ms partial 2.65ms ``` After: ``` Generating tablet metadata Total tablet count: 131072 Size of tablet_metadata in memory: 59504 KiB Copied in 0.032475 [ms] Cleared in 0.002965 [ms] Saved in 1093.877441 [ms] Read in 387.027100 [ms] Read mutations in 255.752121 [ms] 128 mutations Read required hosts in 211.202805 [ms] Size of canonical mutations: 33.954453 [MiB] Disk space used by system.tablets: 1.450162 [MiB] Tablet metadata reload: full 354.50ms partial 2.19ms ``` Closes scylladb/scylladb#28459 * github.com:scylladb/scylladb: test: boost: tablets: Add test for merge with arbitrary tablet count tablets, database: Advertise 'arbitrary' layout in snapshot manifest tablets: Introduce pow2_count per-table tablet option tablets: Prepare for non-power-of-two tablet count tablets: Implement merged tablet_map constructor on top of for_each_sibling_tablets() tablets: Prepare resize_decision to hold data in decisions tablets: table: Make storage_group handle arbitrary merge boundaries tablets: Make stats update post-merge work with arbitrary merge boundaries locator: tablets: Support arbitrary tablet boundaries locator: tablets: Introduce tablet_map::get_split_token() dht: Introduce get_uniform_tokens()
ScyllaDB Documentation
This repository contains the source files for ScyllaDB 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 and are sources for docs.scylladb.com/manual.
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
- 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.
- Follow the ScyllaDB Style Guide.
To prevent the build from failing:
-
If you add a new file, ensure it's added to an appropriate toctree, for example:
.. toctree:: :maxdepth: 2 :hidden: Page X </folder1/article1> Page Y </folder1/article2> Your New Page </folder1/your-new-article> -
Make sure the link syntax is correct. See the guidelines on creating links
-
Make sure the section headings are correct. See the guidelines on creating headings Note that the markup must be at least as long as the text in the heading. For example:
---------------------- Prerequisites ----------------------
Building User Documentation
Prerequisites
- Python
- poetry
- make
See the ScyllaDB Sphinx Theme prerequisites to check which versions of the above are currently required.
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 previewin thedocs/directory to 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.