-- test/sql/cardinality.sql
-- pg_tre.min_trigram_freq (cardinality-aware build, 1.2.1-4.4.x).
--
-- Values above 1 dropped the posting trees of trigrams in fewer rows
-- than that.  A trigram missing from the upper tree reads as "in no
-- row" to every scan, so the index returned no rows for rare words
-- (no recheck sees rows the index never returns).  Since 4.5.0 values
-- above 1 are refused; this checks that, and that the index agrees
-- with a sequential scan at the default.

CREATE EXTENSION IF NOT EXISTS pg_tre;

-- Force the shared library (and thus its custom GUCs) to load so that
-- SHOW pg_tre.min_trigram_freq below is recognized even in a backend
-- that has not yet touched a pg_tre index.
LOAD 'pg_tre';

DROP TABLE IF EXISTS card_t CASCADE;
CREATE TABLE card_t (id serial, body text);

-- 5 rows containing 'singleton' (well above any reasonable
-- min_trigram_freq).
INSERT INTO card_t (body)
SELECT 'singleton occurrence ' || i FROM generate_series(1, 5) AS i;

-- 200 rows containing 'frequent'.
INSERT INTO card_t (body)
SELECT 'frequent text body ' || i FROM generate_series(1, 200) AS i;

-- Build with min_trigram_freq=10: rare trigrams (e.g. those from
-- 'singleton occurrence N' that occur in only one row each) get
-- dropped.  We can't ALTER SYSTEM inside a regression test (must
-- not run inside a transaction) so this test simply documents
-- the behavior at the default; the operator-side smoke test
-- covered the actual filtering.
SHOW pg_tre.min_trigram_freq;

CREATE INDEX card_idx ON card_t USING tre (body);

-- Differential: index and seq scan must agree on row sets.
SET enable_seqscan = off;
CREATE TEMP TABLE _idx AS
    SELECT id FROM card_t WHERE body %~~ tre_pattern('frequent', 0);

SET enable_seqscan = on;
SET enable_indexscan = off;
SET enable_bitmapscan = off;
CREATE TEMP TABLE _seq AS
    SELECT id FROM card_t WHERE body %~~ tre_pattern('frequent', 0);

SELECT
    (SELECT count(*) FROM _idx) = (SELECT count(*) FROM _seq) AS counts_agree,
    NOT EXISTS (SELECT 1 FROM _idx EXCEPT SELECT 1 FROM _seq)
    AND NOT EXISTS (SELECT 1 FROM _seq EXCEPT SELECT 1 FROM _idx)
        AS row_sets_agree;

DROP TABLE _idx;
DROP TABLE _seq;
DROP TABLE card_t;

-- Values above 1 are refused (ALTER SYSTEM runs the check hook).
ALTER SYSTEM SET pg_tre.min_trigram_freq = 5;
ALTER SYSTEM SET pg_tre.min_trigram_freq = 1;
ALTER SYSTEM RESET pg_tre.min_trigram_freq;