feat(vector_store)!: replace ChromaDB with Milvus Lite - #154
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jakub-walaszczyk
requested review from
Mateusz-Switala,
MichalSteczko and
filip-komarzyniec
September 11, 2026 12:19
Remove the ChromaDB backend entirely (its `chromadb` dependency carried a
large vulnerability surface) and adopt Milvus Lite as the local, zero-server
vector store. Milvus Lite is the embedded mode of the existing Milvus backend,
so it reuses `MilvusVectorStore` and supports hybrid (dense + BM25) search
that Chroma never had.
- Split the Milvus config in two, both served by `MilvusVectorStore`:
- `MilvusConfig` (provider "milvus") is now remote-server-only and
validates that `uri` is an `http(s)://` URL, so a mistyped `MILVUS_URI`
fails loudly instead of silently spinning up a throwaway local database
in production.
- `MilvusLiteConfig` (provider "milvus_lite") is the explicit embedded
engine, configured by a local `db_path` (env `MILVUS_LITE_DB_PATH`). A
shared `_is_server_url` guard keeps the two validations from drifting
apart, and a blank/whitespace `db_path` is rejected up front instead of
surfacing as an opaque pymilvus error.
- Add `temporary_milvus_lite_store`, a throwaway-store context manager (temp
dir + auto cleanup via `TemporaryDirectory`, logging rather than raising on
a `close()` failure) now backing model pre-selection and judge calibration,
which previously relied on ephemeral in-memory Chroma.
- Remove all Chroma vector-only special-casing: hybrid search and the full
hybrid search space now apply to every backend; `vector_store_type` is
validated against "milvus", "milvus_lite", and "pgvector" via a single
`SUPPORTED_PROVIDERS` list shared between the vector store config and the
default search space.
- Drop the now-unused `vector_store_type` parameter from `AI4RAGSearchSpace`,
`prepare_search_space_with_maas`, and
`get_default_ai4rag_search_space_parameters` - it never varied the
generated search space, only validated against `SUPPORTED_PROVIDERS`,
which every remaining backend now supports identically.
- Swap the dependency `chromadb` -> `pymilvus[milvus-lite]` and delete the
now-obsolete `ensure_sqlite3` ChromaDB compatibility shim.
- Align `VectorStoreSettings` fields (`provider_type`/`collection_name`) with
the payload the event handler actually emits.
- Update tests (real embedded Milvus Lite in the unit tier, plus integration
and functional concurrent-query tests) and all documentation accordingly.
BREAKING CHANGE: `ChromaConfig`, `ChromaVectorStore`, and the "chroma" vector
store provider are removed, along with the `chromadb` dependency.
`MilvusConfig` no longer accepts a local file path as its `uri` (it must be
an `http(s)://` server URL); use `MilvusLiteConfig(db_path=...)` for an
embedded local database. The `vector_store_type` argument is also removed
from `AI4RAGSearchSpace.__init__`, `prepare_search_space_with_maas`, and
`get_default_ai4rag_search_space_parameters`.
Signed-off-by: Jakub Walaszczyk <jwalaszc@redhat.com>
Assisted-by: Claude Code
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Remove the ChromaDB backend entirely (its
chromadbdependency carried a large vulnerability surface) and adopt Milvus Lite as the local, zero-server vector store. Milvus Lite is the embedded mode of the existing Milvus backend, so it reusesMilvusVectorStoreand supports hybrid (dense + BM25) search that Chroma never had.MilvusVectorStore:MilvusConfig(provider "milvus") is now remote-server-only and validates thaturiis anhttp(s)://URL, so a mistypedMILVUS_URIfails loudly instead of silently spinning up a throwaway local database in production.MilvusLiteConfig(provider "milvus_lite") is the explicit embedded engine, configured by a localdb_path(envMILVUS_LITE_DB_PATH).temporary_milvus_lite_store, a throwaway-store context manager (temp dir + auto cleanup) now backing model pre-selection and judge calibration, which previously relied on ephemeral in-memory Chroma.vector_store_typeis validated against "milvus", "milvus_lite", and "pgvector".chromadb->pymilvus[milvus-lite]and delete the now-obsoleteensure_sqlite3ChromaDB compatibility shim.BREAKING CHANGE:
ChromaConfig,ChromaVectorStore, and the "chroma" vector store provider are removed, along with thechromadbdependency.MilvusConfigno longer accepts a local file path as itsuri(it must be anhttp(s)://server URL); useMilvusLiteConfig(db_path=...)for an embedded local database.Assisted-by: Claude Code
Relates to: #153
Resolves:
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