Stores

Stores are an experimental feature to help with querying data using similarity search. It is a low level API that consists of only get, set, delete and find.

For example if you have an embedding of some text and want to find text with similar embeddings. You can create embeddings for chunks of all your text then compare them against the embedding of the text you are searching on.

An embedding here meaning a vector of numbers that represent some information about the text. The embeddings are created from an A.I. model such as BERT or a more traditional method such as word frequency.

Previously you would have to integrate with an external vector database or library directly. With the stores feature you can now do it through the LocalAI API.

Note however that doing a similarity search on embeddings is just one way to do retrieval. A higher level API can take this into account, so this may not be the best place to start.

API overview

There is an internal gRPC API and an external facing HTTP JSON API. We’ll just discuss the external HTTP API, however the HTTP API mirrors the gRPC API. Consult pkg/store/client for internal usage.

Everything is in columnar format meaning that instead of getting an array of objects with a key and a value each. You instead get two separate arrays of keys and values.

Keys are arrays of floating point numbers with a maximum width of 32bits. Values are strings (in gRPC they are bytes).

The key vectors must all be the same length and it’s best for search performance if they are normalized. When addings keys it will be detected if they are not normalized and what length they are.

All endpoints accept a store field which specifies which store to operate on. Stores are created on the fly. By default the in-memory local-store backend is used and no configuration is required, but you can select a different store backend per request (see Backends below).

Backends

Each /stores/* request accepts an optional backend field selecting the store implementation. Two backends ship with LocalAI:

Valkey store backend

The valkey-store backend persists vectors in a Valkey Search server, so the data survives a LocalAI restart — unlike the in-memory default. It requires a reachable server that ships the Valkey Search module (for example the valkey/valkey-bundle image).

Select it by passing "backend": "valkey-store" (or the "valkey" alias) on any /stores/* request:

curl -X POST http://localhost:8080/stores/set \
     -H "Content-Type: application/json" \
     -d '{"backend": "valkey-store", "store": "my-vectors", "keys": [[0.1, 0.2], [0.3, 0.4]], "values": ["foo", "bar"]}'

The connection and index are configured through a model config named after the store (the store field on the request, which is the store’s model ID). Create a YAML in your models directory whose name matches the store, set backend: valkey-store, and put the connection / index settings in the options: list as key:value strings. Because each store resolves its own config, different stores can point at different Valkey servers or use different index settings within one LocalAI process:

name: my-vectors
backend: valkey-store
options:
  - addr:valkey.internal:6379
  - username_env:MY_VALKEY_USER
  - password_env:MY_VALKEY_PASSWORD
  - index_algo:HNSW
  - distance_metric:COSINE

The username_env / password_env options name an environment variable that holds the actual credential rather than putting the secret directly in the YAML. This mirrors cloud-proxy’s api_key_env pattern and lets distinct store configs each reference their own credentials. The direct username / password options still work for backward compatibility, and take precedence when both are set.

When no config exists for a store, the backend connects to localhost:6379 with the defaults below (so the zero-config experience still works).

For COSINE the returned similarities follow the same convention as the local store (1.0 = identical, -1.0 = opposite); internally Valkey returns a cosine distance which the backend converts with similarity = 1 - distance. For L2 and IP the raw Valkey score is returned in similarities (for L2, smaller means closer — the opposite ordering of COSINE); nearest-first ordering of the results is preserved in all cases.

Set

To set some keys you can do

curl -X POST http://localhost:8080/stores/set \
     -H "Content-Type: application/json" \
     -d '{"keys": [[0.1, 0.2], [0.3, 0.4]], "values": ["foo", "bar"]}'

Setting the same keys again will update their values.

On success 200 OK is returned with no body.

Get

To get some keys you can do

curl -X POST http://localhost:8080/stores/get \
     -H "Content-Type: application/json" \
     -d '{"keys": [[0.1, 0.2]]}'

Both the keys and values are returned, e.g: {"keys":[[0.1,0.2]],"values":["foo"]}

The order of the keys is not preserved! If a key does not exist then nothing is returned.

Delete

To delete keys and values you can do

curl -X POST http://localhost:8080/stores/delete \
     -H "Content-Type: application/json" \
     -d '{"keys": [[0.1, 0.2]]}'

If a key doesn’t exist then it is ignored.

On success 200 OK is returned with no body.

Find

To do a similarity search you can do

curl -X POST http://localhost:8080/stores/find 
     -H "Content-Type: application/json" \
     -d '{"topk": 2, "key": [0.2, 0.1]}'

topk limits the number of results returned. The result value is the same as get, except that it also includes an array of similarities. Where 1.0 is the maximum similarity. They are returned in the order of most similar to least.