-- SETUP
CREATE OR REPLACE FUNCTION do_explain(stmt text) RETURNS table(a text) AS
$_$
DECLARE
    ret text;
BEGIN
    FOR ret IN EXECUTE format('EXPLAIN (FORMAT text) %s', stmt) LOOP
        a := ret;
        RETURN next ;
    END LOOP;
END;
$_$
LANGUAGE plpgsql;
CREATE EXTENSION hypopg;
CREATE TABLE hypo (id integer, val text);
INSERT INTO hypo SELECT i, 'line ' || i
FROM generate_series(1,100000) f(i);
ANALYZE hypo;
-- TESTS
SELECT COUNT(*) AS nb
FROM public.hypopg_create_index('SELECT 1;CREATE INDEX ON hypo(id); SELECT 2');
WARNING:  hypopg: SQL order #1 is not a CREATE INDEX statement
WARNING:  hypopg: SQL order #3 is not a CREATE INDEX statement
 nb 
----
  1
(1 row)

SELECT nspname, relname, amname FROM public.hypopg_list_indexes();
 nspname | relname | amname 
---------+---------+--------
 public  | hypo    | btree
(1 row)

-- Should use hypothetical index
SELECT COUNT(*) FROM do_explain('SELECT * FROM hypo WHERE id = 1') e
WHERE e ~ 'Index.*<\d+>btree_hypo.*';
 count 
-------
     1
(1 row)

-- Should use hypothetical index
SELECT COUNT(*) FROM do_explain('SELECT * FROM hypo ORDER BY id') e
WHERE e ~ 'Index.*<\d+>btree_hypo.*';
 count 
-------
     1
(1 row)

-- Should not use hypothetical index
SELECT COUNT(*) FROM do_explain('SELECT * FROM hypo') e
WHERE e ~ 'Index.*<\d+>btree_hypo.*';
 count 
-------
     0
(1 row)

-- Add predicate index
SELECT COUNT(*) AS nb
FROM public.hypopg_create_index('CREATE INDEX ON hypo(id) WHERE id < 5');
 nb 
----
  1
(1 row)

-- This specific index should be used
WITH ind AS (
    SELECT indexrelid, row_number() OVER (ORDER BY indexrelid) AS num
    FROM public.hypopg()
),
regexp AS (
    SELECT regexp_replace(e, '.*<(\d+)>.*', E'\\1', 'g') AS r
    FROM do_explain('SELECT * FROM hypo WHERE id < 3') AS e
)
SELECT num
FROM ind
JOIN regexp ON ind.indexrelid::text = regexp.r;
 num 
-----
   2
(1 row)

-- Specify fillfactor
SELECT COUNT(*) AS NB
FROM public.hypopg_create_index('CREATE INDEX ON hypo(id) WITH (fillfactor = 10)');
 nb 
----
  1
(1 row)

-- Specify an incorrect fillfactor
SELECT COUNT(*) AS NB
FROM public.hypopg_create_index('CREATE INDEX ON hypo(id) WITH (fillfactor = 1)');
ERROR:  value 1 out of bounds for option "fillfactor"
DETAIL:  Valid values are between "10" and "100".
-- Index size estimation
SELECT pg_size_pretty(hypopg_relation_size(indexrelid))
FROM hypopg()
ORDER BY indexrelid;
 pg_size_pretty 
----------------
 2544 kB
 8192 bytes
 4120 kB
(3 rows)

-- locally disable hypoopg
SET hypopg.enabled to false;
-- no hypothetical index should be used
SELECT COUNT(*) FROM do_explain('SELECT * FROM hypo WHERE id = 1') e
WHERE e ~ 'Index.*<\d+>btree_hypo.*';
 count 
-------
     0
(1 row)

-- locally re-enable hypoopg
SET hypopg.enabled to true;
-- hypothetical index should be used
SELECT COUNT(*) FROM do_explain('SELECT * FROM hypo WHERE id = 1') e
WHERE e ~ 'Index.*<\d+>btree_hypo.*';
 count 
-------
     1
(1 row)

-- Remove one hypothetical index
SELECT hypopg_drop_index(indexrelid) FROM hypopg() ORDER BY indexrelid LIMIT 1;
 hypopg_drop_index 
-------------------
 t
(1 row)

-- Remove all the hypothetical indexes
SELECT hypopg_reset();
 hypopg_reset 
--------------
 
(1 row)

-- indexes on expression are not handle
SELECT hypopg_create_index('CREATE INDEX ON hypo (md5(val))');
WARNING:  hypopg: hypothetical indexes on expression are not supported yet
 hypopg_create_index 
---------------------
(0 rows)