Difficulties with new user experience on docker

[jjtolton]

$ docker run -dit --rm  -p 5432:5432 -e 'POSTGRES_PASSWORD=postgres' lanterndata/lantern:latest-pg15
cc6e330dca087bef8370d21ee4925f79b76d05ebc28d7a47840360d7f63a1cf3
 $ psql -h localhost -p 5432 -U postgres -d postgres
Password for user postgres: 
psql (10.23 (Ubuntu 10.23-0ubuntu0.18.04.2), server 15.4 (Debian 15.4-1.pgdg120+1))
WARNING: psql major version 10, server major version 15.
         Some psql features might not work.
Type "help" for help.

postgres=# CREATE EXTENSION lantern;
CREATE EXTENSION
postgres=# CREATE TABLE small_world (id integer, vector real[3]);
CREATE TABLE
postgres=# INSERT INTO small_world (id, vector) VALUES (0, '{0,0,0}'), (1, '{0,0,1}');
INSERT 0 2
postgres=# CREATE INDEX ON small_world USING hnsw (vector);
INFO:  done init usearch index
INFO:  inserted 2 elements
INFO:  done saving 2 vectors
CREATE INDEX
postgres=# CREATE INDEX ON small_world USING hnsw (vector dist_l2sq_ops)
postgres-# WITH (M=2, ef_construction=10, ef=4, dims=3);
ERROR:  unrecognized parameter "dims"
postgres=# CREATE INDEX ON small_world USING hnsw (vector dist_l2sq_ops)
WITH (M=2, ef_construction=10, ef=4, dim=3);
INFO:  done init usearch index
INFO:  inserted 2 elements
INFO:  done saving 2 vectors
CREATE INDEX
postgres=# SELECT id, l2sq_dist(vector, ARRAY[0,0,0]) AS dist
postgres-# FROM small_world ORDER BY vector <-> ARRAY[0,0,0] LIMIT 1;
ERROR:  Operator <-> has no standalone meaning and is reserved for use in vector index lookups only
postgres=# \q

I was able to get it working by changing dims to dim, and omitting the <-> ... operator and subsequent clause, but I'm not sure how important these are for the overall workflow. Thanks for this, I was struggling getting the sqllite extension and pgvector extensions running within a spike efficient timeframe.

[dqii]

Thanks for the report! I'll fix these issues in the README.

Re: the second issue - the index doesn't always get triggered, in particular for small tables. If you run SET enable_seqscan = off; that will ensure that the index is triggered in this case. (You can run SET enable_seqscan = on; to undo this action. Alternatively, if you do not expect the index to get triggered, you can sort by l2sq_dist(vector, array[0,0,0])

We have a note on the operator use in the README for more details.

[raoufchebri]

Facing the same issue: Operator <-> has no standalone meaning and is reserved for use in vector index lookups only

[dqii]

@raoufchebri I just edited the README to clarify --- for small tables, you will need to set enable_seqscan to off, since the index doesn't always get triggered. Please let me know if that helps!

[dqii]

We changed this so that the operator is always used regardless of whether or not the index is created, similar to pgvector, so this should no longer be an issue!