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|
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)
|
