Vectors

The following covers available vector model configuration options.

path

path: string

Sets the path for a vectors model. When using a transformers/sentence-transformers model, this can be any model on the Hugging Face Hub or a local file path. Otherwise, it must be a local file path to a word embeddings model.

method

method: transformers|sentence-transformers|words|external

Sentence embeddings method to use. If the method is not provided, it is inferred using the path.

sentence-transformers and words require the similarity extras package to be installed.

transformers

Builds sentence embeddings using a transformers model. While this can be any transformers model, it works best with models trained to build sentence embeddings.

sentence-transformers

Same as transformers but loads models with the sentence-transformers library.

words

Builds sentence embeddings using a word embeddings model. Transformers models are the preferred vector backend in most cases. Word embeddings models may be deprecated in the future.

storevectors

storevectors: boolean

Enables copying of a vectors model set in path into the embeddings models output directory on save. This option enables a fully encapsulated index with no external file dependencies.

pca

pca: int

Removes n principal components from generated sentence embeddings. When enabled, a TruncatedSVD model is built to help with dimensionality reduction. After pooling of vectors creates a single sentence embedding, this method is applied.

external

Sentence embeddings are loaded via an external model or API. Requires setting the transform parameter to a function that translates data into vectors.

transform

transform: function

When method is external, this function transforms input content into embeddings. The input to this function is a list of data. This method must return either a numpy array or list of numpy arrays.

gpu

gpu: boolean|int|string|device

Set the target device. Supports true/false, device id, device string and torch device instance. This is automatically derived if omitted.

batch

batch: int

Sets the transform batch size. This parameter controls how input streams are chunked and vectorized.

encodebatch

encodebatch: int

Sets the encode batch size. This parameter controls the underlying vector model batch size. This often corresponds to a GPU batch size, which controls GPU memory usage.

tokenize

tokenize: boolean

Enables string tokenization (defaults to false). This method applies tokenization rules that only work with English language text and may increase the quality of English language sentence embeddings in some situations.

instructions

instructions:
    query: prefix for queries
    data: prefix for indexing

Instruction-based models use prefixes to modify how embeddings are computed. This is especially useful with asymmetric search, which is when the query and indexed data are of vastly different lengths. In other words, short queries with long documents.

E5-base is an example of a model that accepts instructions. It takes query: and passage: prefixes and uses those to generate embeddings that work well for asymmetric search.