-- Another extension's create_upper_paths_hook installed AFTER pg_lion's, so
-- the other one is called by core and chains to pg_lion.  Without a preload,
-- pg_lion is loaded on first use by the first query below and lion_hooktest
-- is LOADed after it; with shared_preload_libraries = 'pg_lion,
-- lion_hooktest' the order is the same and the LOAD is a no-op.
\set VERBOSITY terse
SELECT count(*) FROM hk WHERE k = 3;
 count 
-------
  1000
(1 row)

LOAD 'lion_hooktest';
SELECT lion_hooktest_reset();
 lion_hooktest_reset 
---------------------
 
(1 row)

EXPLAIN (COSTS OFF) SELECT count(*) FROM hk WHERE k = 3;
          QUERY PLAN          
------------------------------
 Custom Scan (LionCount)
   Lion Indexes: hk_k (k = 3)
(2 rows)

SELECT count(*) FROM hk WHERE k = 3;
 count 
-------
  1000
(1 row)

EXPLAIN (COSTS OFF) SELECT g, count(*) FROM hk WHERE k IN (1, 2) GROUP BY g;
                          QUERY PLAN                           
---------------------------------------------------------------
 Custom Scan (LionCount)
   Lion Indexes: hk_g (g), hk_k (k = ANY ('{1,2}'::integer[]))
   Group Key: g
(3 rows)

SELECT g, count(*) FROM hk WHERE k IN (1, 2) GROUP BY g ORDER BY g;
 g | count 
---+-------
 1 |  1000
 2 |  1000
(2 rows)

EXPLAIN (COSTS OFF) SELECT k, count(*) FROM hk_p GROUP BY k;
            QUERY PLAN            
----------------------------------
 Finalize HashAggregate
   Group Key: hk_p.k
   ->  Custom Scan (LionCount)
         Partitions: hk_p1, hk_p2
         Lion Indexes: (k)
         Group Key: k
(6 rows)

SELECT k, count(*) FROM hk_p WHERE k IN (0, 7, 19) GROUP BY k ORDER BY k;
 k  | count 
----+-------
  0 |  1000
  7 |  1000
 19 |  1000
(3 rows)

-- the other hook ran, and found pg_lion's path already there each time the
-- previous hook - pg_lion's - returned from a grouped rel it could answer
SELECT lion_hooktest_calls() > 0 AS hooktest_ran,
	   lion_hooktest_saw_lion() AS hooktest_saw_lion_path;
 hooktest_ran | hooktest_saw_lion_path 
--------------+------------------------
 t            |                      6
(1 row)

SET pg_lion.enable_count_pushdown = off;
SELECT count(*) FROM hk WHERE k = 3;
 count 
-------
  1000
(1 row)

SELECT g, count(*) FROM hk WHERE k IN (1, 2) GROUP BY g ORDER BY g;
 g | count 
---+-------
 1 |  1000
 2 |  1000
(2 rows)

SELECT k, count(*) FROM hk_p WHERE k IN (0, 7, 19) GROUP BY k ORDER BY k;
 k  | count 
----+-------
  0 |  1000
  7 |  1000
 19 |  1000
(3 rows)

RESET pg_lion.enable_count_pushdown;
-- the LionOrdered scan (DESIGN.md §30), which set_rel_pathlist_hook adds,
-- chained the same way: the lion filter k = 3 over a walk of the btree on v.
-- The rel hook's counters start here: pg_lion offers ordered paths for the
-- queries above too (an ORDER BY of a lion column walks that column).
SELECT lion_hooktest_reset();
 lion_hooktest_reset 
---------------------
 
(1 row)

SET enable_seqscan = off; SET enable_bitmapscan = off;
SET pg_lion.enable_plain_scan = off; SET enable_indexonlyscan = off;
SET pg_lion.pushdown_margin = 1000;
EXPLAIN (COSTS OFF) SELECT v FROM hk WHERE k = 3 ORDER BY v LIMIT 5;
              QUERY PLAN               
---------------------------------------
 Limit
   ->  Custom Scan (LionOrdered) on hk
         Ordered By: hk_v
         Lion Cond: (k = 3)
         Lion Indexes: hk_k
(5 rows)

SELECT v FROM hk WHERE k = 3 ORDER BY v LIMIT 5;
 v  
----
  3
 23
 43
 63
 83
(5 rows)

RESET enable_seqscan; RESET enable_bitmapscan;
RESET pg_lion.enable_plain_scan; RESET enable_indexonlyscan;
RESET pg_lion.pushdown_margin;
SET pg_lion.enable_ordered_scan = off;
SELECT v FROM hk WHERE k = 3 ORDER BY v LIMIT 5;
 v  
----
  3
 23
 43
 63
 83
(5 rows)

RESET pg_lion.enable_ordered_scan;
-- the other rel hook found pg_lion's path there both times
SELECT lion_hooktest_rel_calls() > 0 AS rel_hook_ran,
	   lion_hooktest_rel_saw_ordered() AS rel_hook_saw_ordered_path;
 rel_hook_ran | rel_hook_saw_ordered_path 
--------------+---------------------------
 t            |                         2
(1 row)

SET pg_lion.no_such_setting = 1;
ERROR:  invalid configuration parameter name "pg_lion.no_such_setting"
SET lion_hooktest.no_such_setting = 1;
ERROR:  invalid configuration parameter name "lion_hooktest.no_such_setting"