CREATE EXTENSION bloom; CREATE TABLE tst ( i int4, t text ); INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i; CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (col1 = 3); ALTER INDEX bloomidx SET (length=80); SET enable_seqscan=on; SET enable_bitmapscan=off; SET enable_indexscan=off; SELECT count(*) FROM tst WHERE i = 7; count ------- 200 (1 row) SELECT count(*) FROM tst WHERE t = '5'; count ------- 112 (1 row) SELECT count(*) FROM tst WHERE i = 7 AND t = '5'; count ------- 13 (1 row) SET enable_seqscan=off; SET enable_bitmapscan=on; SET enable_indexscan=on; EXPLAIN (COSTS OFF) SELECT count(*) FROM tst WHERE i = 7; QUERY PLAN ------------------------------------------- Aggregate -> Bitmap Heap Scan on tst Recheck Cond: (i = 7) -> Bitmap Index Scan on bloomidx Index Cond: (i = 7) (5 rows) EXPLAIN (COSTS OFF) SELECT count(*) FROM tst WHERE t = '5'; QUERY PLAN ------------------------------------------- Aggregate -> Bitmap Heap Scan on tst Recheck Cond: (t = '5'::text) -> Bitmap Index Scan on bloomidx Index Cond: (t = '5'::text) (5 rows) EXPLAIN (COSTS OFF) SELECT count(*) FROM tst WHERE i = 7 AND t = '5'; QUERY PLAN --------------------------------------------------------- Aggregate -> Bitmap Heap Scan on tst Recheck Cond: ((i = 7) AND (t = '5'::text)) -> Bitmap Index Scan on bloomidx Index Cond: ((i = 7) AND (t = '5'::text)) (5 rows) SELECT count(*) FROM tst WHERE i = 7; count ------- 200 (1 row) SELECT count(*) FROM tst WHERE t = '5'; count ------- 112 (1 row) SELECT count(*) FROM tst WHERE i = 7 AND t = '5'; count ------- 13 (1 row) DELETE FROM tst; INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i; VACUUM ANALYZE tst; SELECT count(*) FROM tst WHERE i = 7; count ------- 200 (1 row) SELECT count(*) FROM tst WHERE t = '5'; count ------- 112 (1 row) SELECT count(*) FROM tst WHERE i = 7 AND t = '5'; count ------- 13 (1 row) DELETE FROM tst WHERE i > 1 OR t = '5'; VACUUM tst; INSERT INTO tst SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i; SELECT count(*) FROM tst WHERE i = 7; count ------- 200 (1 row) SELECT count(*) FROM tst WHERE t = '5'; count ------- 112 (1 row) SELECT count(*) FROM tst WHERE i = 7 AND t = '5'; count ------- 13 (1 row) VACUUM FULL tst; SELECT count(*) FROM tst WHERE i = 7; count ------- 200 (1 row) SELECT count(*) FROM tst WHERE t = '5'; count ------- 112 (1 row) SELECT count(*) FROM tst WHERE i = 7 AND t = '5'; count ------- 13 (1 row) -- Try an unlogged table too CREATE UNLOGGED TABLE tstu ( i int4, t text ); INSERT INTO tstu SELECT i%10, substr(md5(i::text), 1, 1) FROM generate_series(1,2000) i; CREATE INDEX bloomidxu ON tstu USING bloom (i, t) WITH (col2 = 4); SET enable_seqscan=off; SET enable_bitmapscan=on; SET enable_indexscan=on; EXPLAIN (COSTS OFF) SELECT count(*) FROM tstu WHERE i = 7; QUERY PLAN -------------------------------------------- Aggregate -> Bitmap Heap Scan on tstu Recheck Cond: (i = 7) -> Bitmap Index Scan on bloomidxu Index Cond: (i = 7) (5 rows) EXPLAIN (COSTS OFF) SELECT count(*) FROM tstu WHERE t = '5'; QUERY PLAN -------------------------------------------- Aggregate -> Bitmap Heap Scan on tstu Recheck Cond: (t = '5'::text) -> Bitmap Index Scan on bloomidxu Index Cond: (t = '5'::text) (5 rows) EXPLAIN (COSTS OFF) SELECT count(*) FROM tstu WHERE i = 7 AND t = '5'; QUERY PLAN --------------------------------------------------------- Aggregate -> Bitmap Heap Scan on tstu Recheck Cond: ((i = 7) AND (t = '5'::text)) -> Bitmap Index Scan on bloomidxu Index Cond: ((i = 7) AND (t = '5'::text)) (5 rows) SELECT count(*) FROM tstu WHERE i = 7; count ------- 200 (1 row) SELECT count(*) FROM tstu WHERE t = '5'; count ------- 112 (1 row) SELECT count(*) FROM tstu WHERE i = 7 AND t = '5'; count ------- 13 (1 row) RESET enable_seqscan; RESET enable_bitmapscan; RESET enable_indexscan; -- Run amvalidator function on our opclasses SELECT opcname, amvalidate(opc.oid) FROM pg_opclass opc JOIN pg_am am ON am.oid = opcmethod WHERE amname = 'bloom' ORDER BY 1; opcname | amvalidate ----------+------------ int4_ops | t text_ops | t (2 rows) -- -- relation options -- DROP INDEX bloomidx; CREATE INDEX bloomidx ON tst USING bloom (i, t) WITH (length=7, col1=4); SELECT reloptions FROM pg_class WHERE oid = 'bloomidx'::regclass; reloptions ------------------- {length=7,col1=4} (1 row) -- check for min and max values \set VERBOSITY terse CREATE INDEX bloomidx2 ON tst USING bloom (i, t) WITH (length=0); ERROR: value 0 out of bounds for option "length" CREATE INDEX bloomidx2 ON tst USING bloom (i, t) WITH (col1=0); ERROR: value 0 out of bounds for option "col1"