-- A conjunction of many terms of very different frequency: the cursors are ordered rarest first and
-- skipped once the page intersection is empty; results equal the document-level evaluation
CREATE EXTENSION pg_sift;
CREATE TABLE am (id serial, body text);
INSERT INTO am (body)
SELECT 'common' || ' mid' || (i % 3) || ' w' || (i % 50) || ' x' || (i % 700) || ' y' || (i % 1999) || ' rare' || (i % 20011)
FROM generate_series(1, 60000) i;
CREATE INDEX am_idx ON am USING sift (body);
CREATE FUNCTION am_ids(q text, via_index boolean) RETURNS text LANGUAGE plpgsql AS $$
BEGIN
	PERFORM set_config('enable_seqscan', (NOT via_index)::text, true);
	PERFORM set_config('enable_bitmapscan', via_index::text, true);
	PERFORM set_config('sift.enable_scan', 'false', true);
	RETURN (SELECT count(*) || ':' || coalesce(sum(id), 0) FROM am WHERE body @@> q);
END $$;
SELECT q, am_ids(q, true) = am_ids(q, false) AS same, am_ids(q, true) AS rows FROM (VALUES
	('common AND mid1 AND w7 AND x7 AND y7 AND rare7'),
	('rare7 AND common AND mid1 AND w7 AND x7 AND y7'),
	('common AND mid2 AND w9 AND x9 AND y9 AND rare9 AND rare20020'),
	('common AND mid0 AND w3 AND x303 AND y303'),
	('common AND mid1 AND w7'),
	('common AND mid0 AND w3 AND x3 AND y3 AND rare3 AND rare4'),
	('(common AND mid1) AND (w7 AND x7) AND (y7 OR y8) AND (rare7 OR rare8)')
) v(q);
                                   q                                   | same |     rows     
-----------------------------------------------------------------------+------+--------------
 common AND mid1 AND w7 AND x7 AND y7 AND rare7                        | t    | 1:7
 rare7 AND common AND mid1 AND w7 AND x7 AND y7                        | t    | 1:7
 common AND mid2 AND w9 AND x9 AND y9 AND rare9 AND rare20020          | t    | 0:0
 common AND mid0 AND w3 AND x303 AND y303                              | t    | 1:303
 common AND mid1 AND w7                                                | t    | 400:11972800
 common AND mid0 AND w3 AND x3 AND y3 AND rare3 AND rare4              | t    | 0:0
 (common AND mid1) AND (w7 AND x7) AND (y7 OR y8) AND (rare7 OR rare8) | t    | 1:7
(7 rows)

-- ranked top-10 of a conjunction with many matches
SELECT count(*) AS ranked FROM (SELECT id FROM am WHERE body @@> 'common AND mid1 AND w7' ORDER BY sift.score(ctid) DESC LIMIT 10) r;
 ranked 
--------
     10
(1 row)

-- ranked units seek their own group only: nested OR / AND NOT across many superblocks
SELECT count(*) AS ranked_nested, bool_and(id % 700 = 7 OR id % 700 = 8) AS nested_ok FROM
	(SELECT id FROM am WHERE body @@> 'common AND (x7 OR x8) AND NOT mid0 AND w7' ORDER BY sift.score(ctid) DESC LIMIT 30) r;
 ranked_nested | nested_ok 
---------------+-----------
            30 | t
(1 row)

SELECT sift.verify('am_idx', true);
 verify 
--------
 
(1 row)

DROP TABLE am;
DROP FUNCTION am_ids;
DROP EXTENSION pg_sift;