-- The reads count what maintenance would spare them (sift.stats), whether or not maintenance may run: rows checked in the heap price a VACUUM, rows of units with a dead row price a rewrite.
CREATE EXTENSION pg_sift;
SET client_min_messages = warning;
CREATE TABLE rp (id int, k int, v int) WITH (autovacuum_enabled = false);
INSERT INTO rp SELECT g, g % 50, g FROM generate_series(1, 20000) g;
CREATE INDEX rp_c ON rp USING sift_col (id, k, v);
VACUUM (ANALYZE, FREEZE) rp;
UPDATE rp SET v = v + 1 WHERE id % 10 = 0;
SET max_parallel_workers_per_gather = 0;
SET sift.col_auto_merge = off;
SELECT k, count(*), sum(v) FROM rp GROUP BY k ORDER BY k LIMIT 2;
SELECT name, value > 0 AS counted FROM sift.stats() WHERE name IN ('rows_vetted', 'read_penalty_kinstr') ORDER BY name;
SELECT name, value FROM sift.stats() WHERE name IN ('rows_dirty_units', 'maintenance_asks') ORDER BY name;
DROP TABLE rp;
DROP EXTENSION pg_sift;