-- Per-row (trigram,tid) de-dup: heavily repetitive text emits one
-- tuple per DISTINCT trigram per row, not per occurrence.  Verify
-- (a) the estimate reflects the small distinct count, and
-- (b) correctness is preserved (index matches == seq-scan matches).
CREATE EXTENSION IF NOT EXISTS pg_tre;
psql:test/sql/build_dedup.sql:5: NOTICE:  extension "pg_tre" already exists, skipping
CREATE EXTENSION
CREATE TABLE dd_t(id serial primary key, body text);
CREATE TABLE
INSERT INTO dd_t(body)
SELECT repeat('needle ', 200) || (CASE WHEN g % 100 = 0 THEN 'rarehay' ELSE '' END)
FROM generate_series(1, 300) g;
INSERT 0 300
ANALYZE dd_t;
ANALYZE
-- repeat('needle ',200) is 1400 bytes/row but a handful of distinct
-- trigrams: est_trigrams/row must be small (dedup working), not ~1400.
SELECT CASE WHEN est_trigrams < 50 * est_rows THEN 'dedup_collapsed'
            ELSE 'dedup_not_working' END AS dedup_result
FROM tre_estimate_index_build('dd_t'::regclass, 2);
  dedup_result   
-----------------
 dedup_collapsed
(1 row)

-- Correctness preserved: index matches must equal seq-scan matches.
CREATE INDEX dd_idx ON dd_t USING tre (body);
psql:test/sql/build_dedup.sql:20: NOTICE:  pg_tre: collected 2121 trigram entries from 300 heap tuples
psql:test/sql/build_dedup.sql:20: NOTICE:  pg_tre: built 14 posting trees
psql:test/sql/build_dedup.sql:20: NOTICE:  pg_tre: build complete, indexed 300 heap tuples into 14 trigrams
CREATE INDEX
SELECT CASE WHEN
  (SELECT count(*) FROM dd_t WHERE body %~~ tre_pattern('needle', 0)) =
  (SELECT count(*) FROM dd_t WHERE body LIKE '%needle%')
  THEN 'needle_correct' ELSE 'needle_wrong' END AS needle_result;
 needle_result  
----------------
 needle_correct
(1 row)

SELECT CASE WHEN
  (SELECT count(*) FROM dd_t WHERE body %~~ tre_pattern('rarehay', 0)) =
  (SELECT count(*) FROM dd_t WHERE body LIKE '%rarehay%')
  THEN 'rare_correct' ELSE 'rare_wrong' END AS rare_result;
 rare_result  
--------------
 rare_correct
(1 row)

DROP TABLE dd_t;
DROP TABLE