Show HN: DuckDB community extension for prefiltered HNSW using ACORN-1

Hacker News (score: 60)
Found: March 25, 2026
ID: 3905

Description

Database
Show HN: DuckDB community extension for prefiltered HNSW using ACORN-1 Hey folks! As someone doing hybrid search daily and wishing I could have a pgvector-like experience but with actual prefiltered approximate nearest neighbours, I decided to just take a punt on implementing ACORN on a fork of the DuckDB VSS extension. I had to make some changes to (vendored) usearch that I'm thinking of submitting upstream. But this does the business. Approximate nearest neighbours with WHERE prefiltering.

Edit: Just to clarify, this has been accepted into the community extensions repo. So you can use it like:

```

INSTALL hnsw_acorn FROM community;

LOAD hnsw_acorn;

```

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