4e984139b2
In this PR we add a basic implementation of the strongly-consistent tables: * generate raft group id when a strongly-consistent table is created * persist it into system.tables table * start raft groups on replicas when a strongly-consistent tablet_map reaches them * add strongly-consistent version of the storage_proxy, with the `query` and `mutate` methods * the `mutate` method submits a command to the tablets raft group, the query method reads the data with `raft.read_barrier()` * strongly-consistent versions of the `select_statement` and `modification_statement` are added * a basic `test_strong_consistency.py/test_basic_write_read` is added which to check that we can write and read data in a strongly consistent fashion. Limitations: * for now the strongly consistent tables can have tablets only on shard zero. This is because we (ab/re) use the existing raft system tables which live only on shard0. In the next PRs we'll create separate tables for the new tablets raft groups. * No Scylla-side proxying - the test has to figure out who is the leader and submit the command to the right node. This will be fixed separately. * No tablet balancing -- migration/split/merges require separate complicated code. The new behavior is hidden behind `STRONGLY_CONSISTENT_TABLES` feature, which is enabled when the `STRONGLY_CONSISTENT_TABLES` experimental feature flag is set. Requirements, specs and general overview of the feature can be found [here](https://scylladb.atlassian.net/wiki/spaces/RND/pages/91422722/Strong+Consistency). Short term implementation plan is [here](https://docs.google.com/document/d/1afKeeHaCkKxER7IThHkaAQlh2JWpbqhFLIQ3CzmiXhI/edit?tab=t.0#heading=h.thkorgfek290) One can check the strongly consistent writes and reads locally via cqlsh: scylla.yaml: ``` experimental_features: - strongly-consistent-tables ``` cqlsh: ``` CREATE KEYSPACE IF NOT EXISTS my_ks WITH replication = {'class': 'NetworkTopologyStrategy', 'replication_factor': 1} AND tablets = {'initial': 1} AND consistency = 'local'; CREATE TABLE my_ks.test (pk int PRIMARY KEY, c int); INSERT INTO my_ks.test (pk, c) VALUES (10, 20); SELECT * FROM my_ks.test WHERE pk = 10; ``` Fixes SCYLLADB-34 Fixes SCYLLADB-32 Fixes SCYLLADB-31 Fixes SCYLLADB-33 Fixes SCYLLADB-56 backport: no need Closes scylladb/scylladb#27614 * https://github.com/scylladb/scylladb: test_encryption: capture stderr test/cluster: add test_strong_consistency.py raft_group_registry: disable metrics for non-0 groups strong consistency: implement select_statement::do_execute() cql: add select_statement.cc strong consistency: implement coordinator::query() cql: add modification_statement cql: add statement_helpers strong consistency: implement coordinator::mutate() raft.hh: make server::wait_for_leader() public strong_consistency: add coordinator modification_statement: make get_timeout public strong_consistency: add groups_manager strong_consistency: add state_machine and raft_command table: add get_max_timestamp_for_tablet tablets: generate raft group_id-s for new table tablet_replication_strategy: add consistency field tablets: add raft_group_id modification_statement: remove virtual where it's not needed modification_statement: inline prepare_statement() system_keyspace: disable tablet_balancing for strongly_consistent_tables cql: rename strongly_consistent statements to broadcast statements
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.
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To prevent the build from failing:
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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
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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
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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
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This document includes material from Apache Cassandra.
Apache Cassandra is Copyright 2009-2014 The Apache Software Foundation.