ERROR: access method "hnsw" does not exist

[timdonovanuk]

Hi,

Long story short, I'm accidentally running pgvetor 0.3-alpha and the app I'm using (immich) requires 0.2. I have not run into any issues apart from creating this index:

CREATE INDEX IF NOT EXISTS face_index ON asset_faces
    USING hnsw (embedding vector_cosine_ops)
    WITH (ef_construction = 300, m = 16);

where I get the error access method "hnsw" does not exist.

Indeed it does not exist:

SELECT amname AS index_method FROM pg_am WHERE amtype = 'i'

index_method:

btree
hash
gist
gin
spgist
brin
vectors

I've tried SET vectors.pgvector_compatibility=on too.

How do I create this index access method? Thank you

[cutecutecat]

Hello, thanks for your report.
Yes, the access method hnsw does not exist in pgvecto.rs.
We support it by vectors.pgvector_compatibility and rewrite hnsw to vectors internally.

This feature requires SET vectors.pgvector_compatibility=on in current session.
Do you set it in the same session of CREATE INDEX like:

postgres=# CREATE TABLE t (val vector(3));
CREATE TABLE
postgres=# INSERT INTO t (val) SELECT ARRAY[random(), random(), random()]::real[] FROM generate_series(1, 1000);
INSERT 0 1000
postgres=# CREATE INDEX hnsw_l2_index ON t USING hnsw (val vector_l2_ops);
ERROR:  access method "hnsw" does not exist
postgres=# SET vectors.pgvector_compatibility=on;
SET
postgres=# CREATE INDEX hnsw_l2_index ON t USING hnsw (val vector_l2_ops);
CREATE INDEX
postgres=# 

Or ALTER SYSTEM SET vectors.pgvector_compatibility=on may help you to set it globally.

If that not worked, could you please show us some steps to reproduce?