`pgvector` compatibility

pgvecto.rs is natively compatible with pgvector at:

pgvecto.rs is natively compatible with pgvector at:

CREATE TABLE commands, e.g. CREATE TABLE t (val vector(3))
INSERT INTO commands, e.g. INSERT INTO t (val) VALUES ('[0.6,0.6,0.6]')

pgvecto.rs can be configured to be compatible with pgvector at:

Index options, which allows you to create index by USING hnsw (val vector_ip_ops)
Query options, which can be set by SET ivfflat.probes = 10

This feature is named pgvector compatibility. It can be enabled by SET vectors.pgvector_compatibility = on.

Index Options & Query Options

For index ivfflat and hnsw only the following options are available.

Default value for index options is different from pgvecto.rs original, which keeps the same as in pgvector.
Default value for query options is the same as in pgvecto.rs.

Index options for ivfflat:

Key	Type	Range	Default	Description
nlist	integer	`[1, 1_000_000]`	`100`	Number of cluster units.

Query options for ivfflat:

Option	Type	Range nn	Default	Description
ivfflat.probes	integer	`[1, 1_000_000]`	`10`	Number of lists to scan.

Warning

Default value of ivfflat.probes is 10 instead of 1 from pgvector.

Index options for hnsw:

Key	Type	Range	Default	Description
m	integer	`[4, 128]`	`16`	Maximum degree of the node.
ef_construction	integer	`[10, 2000]`	`64`	Search scope in building.

Query options for hnsw:

Option	Type	Range	Default	Description
hnsw.ef_search	integer	`[1, 65535]`	`100`	Search scope of HNSW.

Warning

Default value for hnsw.ef_search is 100 instead of 40 from pgvector.

Examples

It’s easy to enable pgvector compatibility and start a vector query.

DROP TABLE IF EXISTS t;
SET vectors.pgvector_compatibility=on;
SET hnsw.ef_search=40;
CREATE TABLE t (val vector(3));
INSERT INTO t (val) SELECT ARRAY[random(), random(), random()]::real[] FROM generate_series(1, 1000);
CREATE INDEX hnsw_cos_index ON t USING hnsw (val vector_cosine_ops);
SELECT COUNT(1) FROM (SELECT 1 FROM t ORDER BY val <-> '[0.5,0.5,0.5]' limit 100) t2;
DROP INDEX hnsw_cos_index;

Multiply types of indexes are accepted:

SET vectors.pgvector_compatibility=on;
SET hnsw.ef_search=40;
-- [hnsw + vector_l2_ops] index with default options
CREATE INDEX hnsw_l2_index ON t USING hnsw (val vector_l2_ops);
-- [hnsw + vector_cosine_ops] index with single ef_construction option
CREATE INDEX hnsw_cosine_index ON t USING hnsw (val vector_cosine_ops) WITH (ef_construction = 80);
-- anonymous [hnsw + vector_ip_ops] with all options
CREATE INDEX ON t USING hnsw (val vector_ip_ops) WITH (ef_construction = 80, m = 12);
SET ivfflat.probes=1;
-- [ivfflat + vector_l2_ops] index with default options
CREATE INDEX ivfflat_l2_index ON t USING ivfflat (val vector_l2_ops);
-- [ivfflat + vector_ip_ops] index with all options
CREATE INDEX ivfflat_ip_index ON t USING ivfflat (val vector_cosine_ops) WITH (nlist = 80);
-- anonymous [ivf + vector_ip_ops] with all options
CREATE INDEX ON t USING ivfflat (val vector_ip_ops) WITH (lists = 80)