-- VACUUM of a sift_col index and of a BM25 index with deleted rows in units of the most rows, 74,496 (14 of them in 1,042,944 rows): a table of one column that is NULL in every row
-- has 291 rows on a heap page, the most, so its units of 256 pages hold 74,496, and the liveness bits of such a unit (9,312 bytes) lie on three pages, which with the header page fill one
-- GenericXLog record (the same bound as tbl_vacuum_dead_span, for the other two kinds of index). The rows deleted are those at every 20th offset of a page, so that every unit has dead rows over its whole length.
-- One builder writes the sift_col segment, of 14 units: two builders write two of seven, whose bits lie on three pages at most. With the arrays of sift_live_clear at three entries, this test fails for both indexes.
CREATE EXTENSION pg_sift;
SET client_min_messages = warning;
CREATE TABLE lc (a int) WITH (autovacuum_enabled = off);
INSERT INTO lc SELECT NULL FROM generate_series(1, 1042944);
VACUUM (FREEZE, ANALYZE) lc;
SELECT max((ctid::text::point)[1]) AS rows_on_a_page FROM lc;
 rows_on_a_page 
----------------
            291
(1 row)

SET max_parallel_maintenance_workers = 0;
CREATE INDEX lc_col ON lc USING sift_col (a);
DELETE FROM lc WHERE (ctid::text::point)[1]::int % 20 = 5;
VACUUM lc;
SELECT count(*) AS live FROM lc;
  live  
--------
 989184
(1 row)

-- and again, in units whose liveness was cleared once
DELETE FROM lc WHERE (ctid::text::point)[1]::int % 20 = 6;
VACUUM (FREEZE) lc;
SELECT count(*) AS live FROM lc;
  live  
--------
 935424
(1 row)

SELECT count(*) AS live_by_a_scan_of_the_index FROM lc WHERE a IS NULL;
 live_by_a_scan_of_the_index 
-----------------------------
                      935424
(1 row)

SELECT sift.col_verify('lc_col', true);
 col_verify 
------------
 
(1 row)

DROP INDEX lc_col;
CREATE INDEX lc_bm ON lc USING sift ((coalesce(a::text, 'x')));
DELETE FROM lc WHERE (ctid::text::point)[1]::int % 20 = 7;
VACUUM lc;
SELECT count(*) AS live FROM lc;
  live  
--------
 881664
(1 row)

SELECT sift.verify('lc_bm');
 verify 
--------
 
(1 row)

DROP TABLE lc;
DROP EXTENSION pg_sift;