26671d4d5f
This series improves the readability and structure of
view_update_builder, the component that generates materialized view
updates from base-table mutations.
The first four patches are pure renames and refactoring with no
semantic changes:
1. Document that the builder operates on a single base partition.
2. Rename member fields to clearly distinguish readers (the
mutation_reader streams) from the cached fragments (the last
mutation_fragment_v2 read from each stream).
3. Rename advance/on_results methods to names that describe what
they actually do: read the next fragment, or generate view
updates.
4. Extract partition-start handling into its own method.
The next two patches are minor optimizations:
5. Simplify clustering-row handling by moving the row out of the
fragment before applying the tombstone, avoiding an unnecessary
memory-usage recalculation in the reader permit.
6. Replace deep copies with moves in the existing-only tail path,
matching the pattern used everywhere else.
Finally, patch 7 deduplicates the fragment-consuming logic by
extracting the three repeated blocks into consume_both_fragments(),
consume_update_fragment(), and consume_existing_fragment().
Code reorganization - no backport needed
Closes scylladb/scylladb#29497
* github.com:scylladb/scylladb:
mv: deduplicate code for consuming fragments in view_update_builder
mv: avoid unnecessary copies of existing rows in generate_updates()
mv: simplify clustering row handling in generate_updates()
mv: rename methods in view_update_builder for clarity
mv: rename view_update_builder readers and cached fragments
mv: drop redundant std::move from partition key extraction
mv: document single-partition builder scope
Scylla
What is Scylla?
Scylla is the real-time big data database that is API-compatible with Apache Cassandra and Amazon DynamoDB. Scylla embraces a shared-nothing approach that increases throughput and storage capacity to realize order-of-magnitude performance improvements and reduce hardware costs.
For more information, please see the ScyllaDB web site.
Build Prerequisites
Scylla is fairly fussy about its build environment, requiring very recent versions of the C++23 compiler and of many libraries to build. The document HACKING.md includes detailed information on building and developing Scylla, but to get Scylla building quickly on (almost) any build machine, Scylla offers a frozen toolchain. This is a pre-configured Docker image which includes recent versions of all the required compilers, libraries and build tools. Using the frozen toolchain allows you to avoid changing anything in your build machine to meet Scylla's requirements - you just need to meet the frozen toolchain's prerequisites (mostly, Docker or Podman being available).
Building Scylla
Building Scylla with the frozen toolchain dbuild is as easy as:
$ git submodule update --init --force --recursive
$ ./tools/toolchain/dbuild ./configure.py
$ ./tools/toolchain/dbuild ninja build/release/scylla
For further information, please see:
- Developer documentation for more information on building Scylla.
- Build documentation on how to build Scylla binaries, tests, and packages.
- Docker image build documentation for information on how to build Docker images.
Running Scylla
To start Scylla server, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --workdir tmp --smp 1 --developer-mode 1
This will start a Scylla node with one CPU core allocated to it and data files stored in the tmp directory.
The --developer-mode is needed to disable the various checks Scylla performs at startup to ensure the machine is configured for maximum performance (not relevant on development workstations).
Please note that you need to run Scylla with dbuild if you built it with the frozen toolchain.
For more run options, run:
$ ./tools/toolchain/dbuild ./build/release/scylla --help
Testing
See test.py manual.
Scylla APIs and compatibility
By default, Scylla is compatible with Apache Cassandra and its API - CQL. There is also support for the API of Amazon DynamoDB™, which needs to be enabled and configured in order to be used. For more information on how to enable the DynamoDB™ API in Scylla, and the current compatibility of this feature as well as Scylla-specific extensions, see Alternator and Getting started with Alternator.
Documentation
Documentation can be found here. Seastar documentation can be found here. User documentation can be found here.
Training
Training material and online courses can be found at Scylla University. The courses are free, self-paced and include hands-on examples. They cover a variety of topics including Scylla data modeling, administration, architecture, basic NoSQL concepts, using drivers for application development, Scylla setup, failover, compactions, multi-datacenters and how Scylla integrates with third-party applications.
Contributing to Scylla
If you want to report a bug or submit a pull request or a patch, please read the contribution guidelines.
If you are a developer working on Scylla, please read the developer guidelines.
Contact
- The community forum and Slack channel are for users to discuss configuration, management, and operations of ScyllaDB.
- The developers mailing list is for developers and people interested in following the development of ScyllaDB to discuss technical topics.