Why dot product isn't available?

[matrs]

I work with normalized vectors, so the dot product of two vectors is equivalent to their cosine similarity. I trying CF vectorize and Qdrant and both have that operation available. To my surprise, it seems the dot product isn't available in libsql. Why is the reason the simplest operation isn't supported?

[onestardao]

hi, quick take.

short reason: libsql itself does not provide a built in dot operator because vector math is usually handled by extensions or by the vector index layer, not by the core SQL engine. that design keeps the DB small and lets specialised extensions (pgvector, qdrant, etc) implement fast, numeric routines.

what you can do now, pick one:

1. use an extension or vector index that exposes dot or cosine directly. that is the cleanest and fastest path.
2. store vectors as SQL arrays and add a tiny UDF that computes dot product over arrays. works fine for small scale.
3. compute the dot in your application layer at query time and pass scores into SQL when needed. simple and safe.
4. contribute an extension/PR to add a server side operator if you need it native and fast.

quick checks for you:
• does your libsql build include a vector extension (pgvector or similar)?
• how are you storing vectors, arrays or binary blobs?
• are vectors already normalized (so dot equals cosine)?

if you want, paste one example row (sanitised) and i’ll give a minimal SQL snippet for computing dot over an array, or a tiny UDF you can drop into the DB. say "show snippet" and i’ll paste it.

[matrs]

Thanks for your answer. I thought that libsql handle vectors natively:

We're enabling all this in libSQL, the Open Contribution fork of SQLite that powers Turso

https://turso.tech/blog/turso-brings-native-vector-search-to-sqlite

That's why I asked this question here.

[onestardao]

thanks that link is useful. short answer: native dot operator is not part of upstream libsql core; vector ops are usually provided by a vector index or an extension. turso’s blog shows a fork/extension path that enables native vector search, so whether you get a dot operator depends on which build you run.

quick checks: are you running the turso/vector-enabled build or plain libsql? how are you storing vectors (array, blob)? are the vectors already normalized?

if you want, paste one sanitized row and i’ll drop a tiny SQL snippet or a UDF you can try. no need to change infra.