SET enable_seqscan = off; -- L2 CREATE TABLE t (val vector(3)); INSERT INTO t (val) VALUES ('[0,0,0]'), ('[1,2,3]'), ('[1,1,1]'), (NULL); CREATE INDEX ON t USING ivfflat (val vector_l2_ops) WITH (lists = 1); INSERT INTO t (val) VALUES ('[1,2,4]'); SELECT * FROM t ORDER BY val <-> '[3,3,3]'; SELECT COUNT(*) FROM (SELECT * FROM t ORDER BY val <-> (SELECT NULL::vector)) t2; SELECT COUNT(*) FROM t; TRUNCATE t; SELECT * FROM t ORDER BY val <-> '[3,3,3]'; DROP TABLE t; -- inner product CREATE TABLE t (val vector(3)); INSERT INTO t (val) VALUES ('[0,0,0]'), ('[1,2,3]'), ('[1,1,1]'), (NULL); CREATE INDEX ON t USING ivfflat (val vector_ip_ops) WITH (lists = 1); INSERT INTO t (val) VALUES ('[1,2,4]'); SELECT * FROM t ORDER BY val <#> '[3,3,3]'; SELECT COUNT(*) FROM (SELECT * FROM t ORDER BY val <#> (SELECT NULL::vector)) t2; DROP TABLE t; -- cosine CREATE TABLE t (val vector(3)); INSERT INTO t (val) VALUES ('[0,0,0]'), ('[1,2,3]'), ('[1,1,1]'), (NULL); CREATE INDEX ON t USING ivfflat (val vector_cosine_ops) WITH (lists = 1); INSERT INTO t (val) VALUES ('[1,2,4]'); SELECT * FROM t ORDER BY val <=> '[3,3,3]'; SELECT COUNT(*) FROM (SELECT * FROM t ORDER BY val <=> '[0,0,0]') t2; SELECT COUNT(*) FROM (SELECT * FROM t ORDER BY val <=> (SELECT NULL::vector)) t2; DROP TABLE t; -- unlogged CREATE UNLOGGED TABLE t (val vector(3)); INSERT INTO t (val) VALUES ('[0,0,0]'), ('[1,2,3]'), ('[1,1,1]'), (NULL); CREATE INDEX ON t USING ivfflat (val vector_l2_ops) WITH (lists = 1); SELECT * FROM t ORDER BY val <-> '[3,3,3]'; DROP TABLE t; -- options CREATE TABLE t (val vector(3)); CREATE INDEX ON t USING ivfflat (val vector_l2_ops) WITH (lists = 0); CREATE INDEX ON t USING ivfflat (val vector_l2_ops) WITH (lists = 32769); SHOW ivfflat.probes; DROP TABLE t;