96dd3121e7
CassIO (the library backing LangChain's `langchain_community.vectorstores.Cassandra` integration) issues the following DDL during schema setup to create a metadata index: ```sql CREATE CUSTOM INDEX IF NOT EXISTS eidx_metadata_s_<table> ON <keyspace>.<table> (ENTRIES(metadata_s)) USING 'org.apache.cassandra.index.sai.StorageAttachedIndex'; ``` ScyllaDB does not support Cassandra's StorageAttachedIndex (SAI) for non-vector columns and previously rejected this statement with: ``` StorageAttachedIndex (SAI) is only supported on vector columns; use a secondary index for non-vector columns ``` This blocks seamless migration of existing LangChain/CassIO applications from Cassandra to ScyllaDB — applications fail during initialization before any application-level workaround can run, even when metadata filtering is not used (`metadata_indexing="none"`). CassIO is no longer actively maintained but remains the only official LangChain integration path for Apache Cassandra over CQL, meaning existing applications will continue using this setup pattern. Instead of rejecting the CassIO metadata-map SAI DDL, detect the pattern and rewrite it to a standard ScyllaDB secondary index on collection entries: - **Detection**: SAI class name + single `ENTRIES` target on a non-frozen `map` column - **Rewrite**: Clear the custom class so the index is created through the standard secondary index path (which already fully supports indexing map entries) - **Warning**: Emit a CQL warning informing the user that SAI is not supported by ScyllaDB, a regular secondary index was created instead, and metadata filtering behavior may differ from Cassandra SAI The rewrite is placed early in `validate_while_executing()`, before the rf-rack-validity check, so the standard secondary index code path handles all subsequent validation naturally — no code duplication. After this change, the CassIO schema setup succeeds on ScyllaDB: - `CREATE CUSTOM INDEX ... USING 'sai'` on `ENTRIES(metadata_s)` creates a real secondary index - The index is functional and can accelerate metadata filtering queries - A CQL warning makes the rewrite transparent to operators - SAI on non-vector, non-map-entries columns is still rejected as before - Vector SAI indexes continue to be rewritten to `vector_index` as before - `test_sai_entries_on_map_creates_regular_index` — verifies the index is created and the warning is emitted (fully-qualified SAI class name) - `test_sai_entries_on_map_short_name` — same with the `'sai'` short alias - `test_sai_on_regular_column_rejected` — confirms SAI on regular scalar columns is still rejected All 148 tests in `test_vector_index.py` and `test_secondary_index.py` pass with no regressions (125 passed, 22 xfailed, 1 skipped). Fixes: SCYLLADB-2113 Backport: 2026.2 as this is the version where the support for SAI class needed by LangChain was added. Closes scylladb/scylladb#29981 * github.com:scylladb/scylladb: cql: rewrite CassIO SAI metadata index to regular secondary index db/config: add enable_cassio_compatibility flag
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.