[Bug]: What's between DefaultEmbeddingFunction() and SentenceTransformerEmbeddingFunction(model_name="all-MiniLM-L6-v2")?

[h3clikejava]

What happened?

I save some embeddings by default like this:
collection = client.get_or_create_collection(name=db_name)

Then, i can fetch data by DefaultEmbeddingFunction() like:
emb_fn = embedding_functions.DefaultEmbeddingFunction()
collection = client.get_or_create_collection(name=db_name, embedding_function=emb_fn) # It's work

But i can't fetch data by all-MiniLM-L6-v2 like:
emb_fn = embedding_functions.SentenceTransformerEmbeddingFunction(model_name="all-MiniLM-L6-v2")
collection = client.get_or_create_collection(name=db_name, embedding_function=emb_fn) # It's not work

What's the different between DefaultEmbeddingFunction and SentenceTransformerEmbeddingFunction(model_name="all-MiniLM-L6-v2")?

Versions

ChromaDB V0.5.3, python v3.10.11, MacOS 15.0 Beta (24A5327a)

Relevant log output

No response

[tazarov]

@h3clikejava, thanks for raising this. Let's start with some background:

• Default EF uses onnx runtime + mean pooling, resulting in 384-dimensional embeddings
• ST does everything out of the box and again produces 384-dimensional embeddings

Under normal circumstances, you should not have trouble swapping between the two, as Chroma will accept queries using 384-dimensional embeddings even though there are slight differences in the output embeddings (in the order of 1-e4/1-e5 range).

That said, when you say it won't work, do you mean you get an error? Can you share the error?

[jeffchuber]

@h3clikejava happy to re-open if you can help out! closing for now as @tazarov did a good job addressing it