--
-- PG17
--
SHOW server_version \gset
SELECT substring(:'server_version', '\d+')::int >= 17 AS server_version_ge_17
\gset
-- PG17 has the capabilty to pull up a correlated ANY subquery to a join if
-- the subquery only refers to its immediate parent query. Previously, the
-- subquery needed to be implemented as a SubPlan node, typically as a
-- filter on a scan or join node. This PG17 capability enables Citus to
-- run queries with correlated subqueries in certain cases, as shown here.
-- Relevant PG commit:
-- https://git.postgresql.org/gitweb/?p=postgresql.git;a=commitdiff;h=9f1337639
-- This feature is tested for all PG versions, not just PG17; each test query with
-- a correlated subquery should fail with PG version < 17.0, but the test query
-- rewritten to reflect how PG17 optimizes it should succeed with PG < 17.0
CREATE SCHEMA pg17_corr_subq_folding;
SET search_path TO pg17_corr_subq_folding;
SET citus.next_shard_id TO 20240017;
SET citus.shard_count TO 2;
SET citus.shard_replication_factor TO 1;
CREATE TABLE test (x int, y int);
SELECT create_distributed_table('test', 'x');
 create_distributed_table
---------------------------------------------------------------------

(1 row)

INSERT INTO test VALUES (1,1), (2,2);
-- Query 1: WHERE clause has a correlated subquery with a UNION. PG17 can plan
-- this as a nested loop join with the subquery as the inner. The correlation
-- is on the distribution column so the join can be pushed down by Citus.
explain (costs off)
SELECT *
FROM test a
WHERE x IN (SELECT x FROM test b UNION SELECT y FROM test c WHERE a.x = c.x)
ORDER BY 1,2;
ERROR:  cannot push down this subquery
DETAIL:  Complex subqueries and CTEs are not supported within a UNION
SET client_min_messages TO DEBUG2;
SELECT *
FROM test a
WHERE x IN (SELECT x FROM test b UNION SELECT y FROM test c WHERE a.x = c.x)
ORDER BY 1,2;
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  generating subplan XXX_1 for subquery SELECT x FROM pg17_corr_subq_folding.test b
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT x, y FROM pg17_corr_subq_folding.test a WHERE (x OPERATOR(pg_catalog.=) ANY (SELECT intermediate_result.x FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(x integer) UNION SELECT c.y FROM pg17_corr_subq_folding.test c WHERE (a.x OPERATOR(pg_catalog.=) c.x))) ORDER BY x, y
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
ERROR:  cannot push down this subquery
DETAIL:  Complex subqueries and CTEs are not supported within a UNION
RESET client_min_messages;
-- Query 1 rewritten with subquery pulled up to a join, as done by PG17 planner;
-- this query can be run without issues by Citus with older (pre PG17) PGs.
explain (costs off)
SELECT a.*
FROM test a JOIN LATERAL (SELECT x FROM test b UNION SELECT y FROM test c WHERE a.x = c.x) dt1 ON a.x = dt1.x
ORDER BY 1,2;
                              QUERY PLAN
---------------------------------------------------------------------
 Sort
   Sort Key: remote_scan.x, remote_scan.y
   ->  Custom Scan (Citus Adaptive)
         Task Count: 2
         Tasks Shown: One of 2
         ->  Task
               Node: host=localhost port=xxxxx dbname=regression
               ->  Nested Loop
                     ->  Seq Scan on test_20240017 a
                     ->  Subquery Scan on dt1
                           Filter: (a.x = dt1.x)
                           ->  HashAggregate
                                 Group Key: b.x
                                 ->  Append
                                       ->  Seq Scan on test_20240017 b
                                       ->  Seq Scan on test_20240017 c
                                             Filter: (a.x = x)
(17 rows)

SET client_min_messages TO DEBUG2;
SELECT a.*
FROM test a JOIN LATERAL (SELECT x FROM test b UNION SELECT y FROM test c WHERE a.x = c.x) dt1 ON a.x = dt1.x
ORDER BY 1,2;
DEBUG:  Router planner cannot handle multi-shard select queries
 x | y
---------------------------------------------------------------------
 1 | 1
 2 | 2
(2 rows)

RESET client_min_messages;
CREATE TABLE users (user_id int, time int, dept int, info bigint);
CREATE TABLE events (user_id int, time int, event_type int, payload text);
select create_distributed_table('users', 'user_id');
 create_distributed_table
---------------------------------------------------------------------

(1 row)

select create_distributed_table('events', 'user_id');
 create_distributed_table
---------------------------------------------------------------------

(1 row)

insert into users
select i, 2021 + (i % 3), i % 5, 99999 * i from generate_series(1, 10) i;
insert into events
select i % 10 + 1, 2021 + (i % 3), i %11, md5((i*i)::text) from generate_series(1, 100) i;
-- Query 2. In Citus correlated subqueries can not be used in the WHERE
-- clause but if the subquery can be pulled up to a join it becomes possible
-- for Citus to run the query, per this example. Pre PG17 the suqbuery
-- was implemented as a SubPlan filter on the events table scan.
EXPLAIN (costs off)
WITH event_id
     AS(SELECT user_id AS events_user_id,
                time    AS events_time,
                event_type
         FROM   events)
SELECT Count(*)
FROM   event_id
WHERE  (events_user_id) IN (SELECT user_id
                          FROM   users
                          WHERE  users.time = events_time);
ERROR:  correlated subqueries are not supported when the FROM clause contains a CTE or subquery
SET client_min_messages TO DEBUG2;
WITH event_id
     AS(SELECT user_id AS events_user_id,
                time    AS events_time,
                event_type
         FROM   events)
SELECT Count(*)
FROM   event_id
WHERE  (events_user_id) IN (SELECT user_id
                          FROM   users
                          WHERE  users.time = events_time);
DEBUG:  CTE event_id is going to be inlined via distributed planning
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  generating subplan XXX_1 for CTE event_id: SELECT user_id AS events_user_id, "time" AS events_time, event_type FROM pg17_corr_subq_folding.events
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT count(*) AS count FROM (SELECT intermediate_result.events_user_id, intermediate_result.events_time, intermediate_result.event_type FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(events_user_id integer, events_time integer, event_type integer)) event_id WHERE (events_user_id OPERATOR(pg_catalog.=) ANY (SELECT users.user_id FROM pg17_corr_subq_folding.users WHERE (users."time" OPERATOR(pg_catalog.=) event_id.events_time)))
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
ERROR:  correlated subqueries are not supported when the FROM clause contains a CTE or subquery
RESET client_min_messages;
-- Query 2 rewritten with subquery pulled up to a join, as done by pg17 planner. Citus
-- Citus is able to run this query with previous pg versions. Note that the CTE can be
-- disregarded because it is inlined, being only referenced once.
EXPLAIN (COSTS OFF)
SELECT Count(*)
FROM (SELECT user_id AS events_user_id,
                time    AS events_time,
                event_type FROM   events) dt1
INNER JOIN (SELECT distinct user_id, time FROM   users) dt
    ON events_user_id = dt.user_id and events_time = dt.time;
                                                 QUERY PLAN
---------------------------------------------------------------------
 Aggregate
   ->  Custom Scan (Citus Adaptive)
         Task Count: 2
         Tasks Shown: One of 2
         ->  Task
               Node: host=localhost port=xxxxx dbname=regression
               ->  Aggregate
                     ->  Hash Join
                           Hash Cond: ((events.user_id = users.user_id) AND (events."time" = users."time"))
                           ->  Seq Scan on events_20240021 events
                           ->  Hash
                                 ->  HashAggregate
                                       Group Key: users.user_id, users."time"
                                       ->  Seq Scan on users_20240019 users
(14 rows)

SET client_min_messages TO DEBUG2;
SELECT Count(*)
FROM (SELECT user_id AS events_user_id,
                time    AS events_time,
                event_type FROM   events) dt1
INNER JOIN (SELECT distinct user_id, time FROM   users) dt
    ON events_user_id = dt.user_id and events_time = dt.time;
DEBUG:  Router planner cannot handle multi-shard select queries
 count
---------------------------------------------------------------------
    31
(1 row)

RESET client_min_messages;
-- Query 3: another example where recursive planning was prevented due to
-- correlated subqueries, but with PG17 folding the subquery to a join it is
-- possible for Citus to plan and run the query.
EXPLAIN (costs off)
SELECT dept, sum(user_id) FROM
(SELECT users.dept, users.user_id
FROM users, events as d1
WHERE d1.user_id = users.user_id
	AND users.dept IN (3,4)
	AND users.user_id IN
	(SELECT s2.user_id FROM users as s2
		GROUP BY d1.user_id, s2.user_id)) dt
GROUP BY dept;
ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
SET client_min_messages TO DEBUG2;
SELECT dept, sum(user_id) FROM
(SELECT users.dept, users.user_id
FROM users, events as d1
WHERE d1.user_id = users.user_id
	AND users.dept IN (3,4)
	AND users.user_id IN
	(SELECT s2.user_id FROM users as s2
		GROUP BY d1.user_id, s2.user_id)) dt
GROUP BY dept;
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  skipping recursive planning for the subquery since it contains references to outer queries
ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
RESET client_min_messages;
-- Query 3 rewritten in a similar way to how the PG17 pulls up the subquery;
-- the join is on the distribution key so Citus can push down.
EXPLAIN (costs off)
SELECT dept, sum(user_id) FROM
(SELECT users.dept, users.user_id
FROM users, events as d1
     JOIN LATERAL (SELECT s2.user_id FROM users as s2
		   GROUP BY s2.user_id HAVING d1.user_id IS NOT NULL) as d2 ON 1=1
WHERE d1.user_id = users.user_id
      AND users.dept IN (3,4)
	AND users.user_id = d2.user_id) dt
GROUP BY dept;
                                         QUERY PLAN
---------------------------------------------------------------------
 HashAggregate
   Group Key: remote_scan.dept
   ->  Custom Scan (Citus Adaptive)
         Task Count: 2
         Tasks Shown: One of 2
         ->  Task
               Node: host=localhost port=xxxxx dbname=regression
               ->  GroupAggregate
                     Group Key: users.dept
                     ->  Sort
                           Sort Key: users.dept
                           ->  Nested Loop
                                 ->  Hash Join
                                       Hash Cond: (d1.user_id = users.user_id)
                                       ->  Seq Scan on events_20240021 d1
                                       ->  Hash
                                             ->  Seq Scan on users_20240019 users
                                                   Filter: (dept = ANY ('{3,4}'::integer[]))
                                 ->  Subquery Scan on d2
                                       Filter: (d1.user_id = d2.user_id)
                                       ->  HashAggregate
                                             Group Key: s2.user_id
                                             ->  Result
                                                   One-Time Filter: (d1.user_id IS NOT NULL)
                                                   ->  Seq Scan on users_20240019 s2
(25 rows)

SET client_min_messages TO DEBUG2;
SELECT dept, sum(user_id) FROM
(SELECT users.dept, users.user_id
FROM users, events as d1
     JOIN LATERAL (SELECT s2.user_id FROM users as s2
		   GROUP BY s2.user_id HAVING d1.user_id IS NOT NULL) as d2 ON 1=1
WHERE d1.user_id = users.user_id
      AND users.dept IN (3,4)
	AND users.user_id = d2.user_id) dt
GROUP BY dept;
DEBUG:  Router planner cannot handle multi-shard select queries
 dept | sum
---------------------------------------------------------------------
    3 | 110
    4 | 130
(2 rows)

SET client_min_messages TO DEBUG3;
CREATE TABLE users_ref(user_id int, dept int);
SELECT create_reference_table('users_ref');
 create_reference_table
---------------------------------------------------------------------

(1 row)

INSERT INTO users_ref VALUES (1, 3), (2, 4), (3, 3), (4, 4);
DEBUG:  Creating router plan
DEBUG:  assigned task to node localhost:xxxxx
-- In PG17, the planner can pull up a correlated ANY subquery to a join, resulting
-- in a different query plan compared to PG16. Specifically, for the following query
-- the rewritten query has a lateral recurring outer join, which requires recursive
-- computation of the inner part. However, this join is not analyzed during the recursive
-- planning step, as it is performed on the original query structure. As a result,
-- the lateral join is not recursively planned, and a lateral join error is raised
-- at a later stage.
SELECT user_id FROM
users RIGHT JOIN users_ref USING (user_id)
WHERE users_ref.dept IN
(
  SELECT events.event_type FROM events WHERE events.user_id = users.user_id
) ORDER BY 1 LIMIT 1;
DEBUG:  no shard pruning constraints on events found
DEBUG:  shard count after pruning for events: 2
DEBUG:  no shard pruning constraints on users found
DEBUG:  shard count after pruning for users: 2
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  a push down safe right join with recurring left side
DEBUG:  push down of limit count: 1
DEBUG:  no shard pruning constraints on events found
DEBUG:  shard count after pruning for events: 2
DEBUG:  no shard pruning constraints on users found
DEBUG:  shard count after pruning for users: 2
DEBUG:  assigned task to node localhost:xxxxx
DEBUG:  assigned task to node localhost:xxxxx
 user_id
---------------------------------------------------------------------
       1
(1 row)

RESET client_min_messages;
RESET search_path;
DROP SCHEMA pg17_corr_subq_folding CASCADE;
NOTICE:  drop cascades to 5 other objects
DETAIL:  drop cascades to table pg17_corr_subq_folding.test
drop cascades to table pg17_corr_subq_folding.users
drop cascades to table pg17_corr_subq_folding.events
drop cascades to table pg17_corr_subq_folding.users_ref
drop cascades to table pg17_corr_subq_folding.users_ref_20240023
-- Queries with outer joins with pseudoconstant quals work only in PG17
-- Relevant PG17 commit:
-- https://github.com/postgres/postgres/commit/9e9931d2b
CREATE SCHEMA pg17_outerjoin;
SET search_path to pg17_outerjoin, public;
SET citus.next_shard_id TO 20250321;
-- issue https://github.com/citusdata/citus/issues/7697
create table t0 (vkey int4 , c3 timestamp);
create table t3 ( vkey int4 ,c26 timestamp);
create table t4 ( vkey int4 );
insert into t0 (vkey, c3) values (13,make_timestamp(2019, 10, 23, 15, 34, 50));
insert into t3 (vkey,c26) values (1, make_timestamp(2024, 3, 26, 17, 36, 53));
insert into t4 (vkey) values (1);
select * from
  (t0 full outer join t3
    on (t0.c3 = t3.c26 ))
where (exists (select  * from t4)) order by 1, 2, 3;
 vkey |            c3            | vkey |           c26
---------------------------------------------------------------------
   13 | Wed Oct 23 15:34:50 2019 |      |
      |                          |    1 | Tue Mar 26 17:36:53 2024
(2 rows)

SELECT create_distributed_table('t0', 'vkey');
NOTICE:  Copying data from local table...
NOTICE:  copying the data has completed
DETAIL:  The local data in the table is no longer visible, but is still on disk.
HINT:  To remove the local data, run: SELECT truncate_local_data_after_distributing_table($$pg17_outerjoin.t0$$)
 create_distributed_table
---------------------------------------------------------------------

(1 row)

select * from
  (t0 full outer join t3
    on (t0.c3 = t3.c26 ))
where (exists (select  * from t4)) order by 1, 2, 3;
ERROR:  Distributed queries with outer joins and pseudoconstant quals are not supported in PG15 and PG16.
DETAIL:  PG15 and PG16 disallow replacing joins with scans when the query has pseudoconstant quals
HINT:  Consider upgrading your PG version to PG17+
-- issue https://github.com/citusdata/citus/issues/7696
create table t1 ( vkey int4 );
create table t2 ( vkey int4 );
insert into t2 (vkey) values (5);
select * from (t2 full outer join t1 on(t2.vkey = t1.vkey ))
where not((85) in (select 1 from t2));
 vkey | vkey
---------------------------------------------------------------------
    5 |
(1 row)

SELECT create_distributed_table('t1', 'vkey');
 create_distributed_table
---------------------------------------------------------------------

(1 row)

SELECT create_reference_table('t2');
NOTICE:  Copying data from local table...
NOTICE:  copying the data has completed
DETAIL:  The local data in the table is no longer visible, but is still on disk.
HINT:  To remove the local data, run: SELECT truncate_local_data_after_distributing_table($$pg17_outerjoin.t2$$)
 create_reference_table
---------------------------------------------------------------------

(1 row)

select * from (t2 full outer join t1 on(t2.vkey = t1.vkey ))
where not((85) in (select 1 from t2));
ERROR:  Distributed queries with outer joins and pseudoconstant quals are not supported in PG15 and PG16.
DETAIL:  PG15 and PG16 disallow replacing joins with scans when the query has pseudoconstant quals
HINT:  Consider upgrading your PG version to PG17+
-- issue https://github.com/citusdata/citus/issues/7698
create table t5 ( vkey int4, c10 int4 );
create table t6 ( vkey int4 );
insert into t5 (vkey,c10) values (4, -70);
insert into t6 (vkey) values (1);
select t6.vkey
from (t5 right outer join t6
    on (t5.c10 = t6.vkey))
where exists (select * from t6);
 vkey
---------------------------------------------------------------------
    1
(1 row)

SELECT create_distributed_table('t5', 'vkey');
NOTICE:  Copying data from local table...
NOTICE:  copying the data has completed
DETAIL:  The local data in the table is no longer visible, but is still on disk.
HINT:  To remove the local data, run: SELECT truncate_local_data_after_distributing_table($$pg17_outerjoin.t5$$)
 create_distributed_table
---------------------------------------------------------------------

(1 row)

select t6.vkey
from (t5 right outer join t6
    on (t5.c10 = t6.vkey))
where exists (select * from t6);
ERROR:  Distributed queries with outer joins and pseudoconstant quals are not supported in PG15 and PG16.
DETAIL:  PG15 and PG16 disallow replacing joins with scans when the query has pseudoconstant quals
HINT:  Consider upgrading your PG version to PG17+
-- issue https://github.com/citusdata/citus/issues/7119
-- this test was removed in
-- https://github.com/citusdata/citus/commit/a5ce601c0
-- Citus doesn't support it in PG15 and PG16, but supports it in PG17
CREATE TABLE users_table_local AS SELECT * FROM users_table;
CREATE TABLE events_table_local AS SELECT * FROM events_table;
SET client_min_messages TO DEBUG1;
-- subquery in FROM -> FROM -> WHERE -> WHERE should be replaced if
-- it contains onle local tables
-- Later the upper level query is also recursively planned due to LIMIT
SELECT user_id, array_length(events_table, 1)
FROM (
  SELECT user_id, array_agg(event ORDER BY time) AS events_table
  FROM (
    SELECT
      u.user_id, e.event_type::text AS event, e.time
    FROM
        users_table AS u,
        events_table AS e
    WHERE u.user_id = e.user_id AND
        u.user_id IN
        (
          SELECT
            user_id
          FROM
            users_table
          WHERE value_2 >= 5
			    AND  EXISTS (SELECT user_id FROM events_table_local WHERE event_type > 1 AND event_type <= 3 AND value_3 > 1)
				AND  NOT EXISTS (SELECT user_id FROM events_table WHERE event_type > 3 AND event_type <= 4  AND value_3 > 1 AND user_id = users_table.user_id)
				LIMIT 5
      )
  ) t
  GROUP BY user_id
) q
ORDER BY 2 DESC, 1;
DEBUG:  generating subplan XXX_1 for subquery SELECT user_id FROM pg17_outerjoin.events_table_local WHERE ((event_type OPERATOR(pg_catalog.>) 1) AND (event_type OPERATOR(pg_catalog.<=) 3) AND (value_3 OPERATOR(pg_catalog.>) (1)::double precision))
ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
RESET search_path;
SET citus.next_shard_id TO 20240023;
SET client_min_messages TO ERROR;
DROP SCHEMA pg17_outerjoin CASCADE;
RESET client_min_messages;
\if :server_version_ge_17
\else
\q