-- ===================================================================
-- test router planner functionality for single shard select queries
-- ===================================================================
-- run all the router queries from the one of the workers
-- prevent PG 11 - PG 12 outputs to diverge
-- and CTE inlining is not relevant to router plannery anyway
SET citus.enable_cte_inlining TO false;
\c - - - :worker_1_port
-- this table is used in a CTE test
CREATE TABLE authors_hash_mx ( name text, id bigint );
-- create a bunch of test data
INSERT INTO articles_hash_mx VALUES ( 1,  1, 'arsenous', 9572);
INSERT INTO articles_hash_mx VALUES ( 2,  2, 'abducing', 13642);
INSERT INTO articles_hash_mx VALUES ( 3,  3, 'asternal', 10480);
INSERT INTO articles_hash_mx VALUES ( 4,  4, 'altdorfer', 14551);
INSERT INTO articles_hash_mx VALUES ( 5,  5, 'aruru', 11389);
INSERT INTO articles_hash_mx VALUES ( 6,  6, 'atlases', 15459);
INSERT INTO articles_hash_mx VALUES ( 7,  7, 'aseptic', 12298);
INSERT INTO articles_hash_mx VALUES ( 8,  8, 'agatized', 16368);
INSERT INTO articles_hash_mx VALUES ( 9,  9, 'alligate', 438);
INSERT INTO articles_hash_mx VALUES (10, 10, 'aggrandize', 17277);
INSERT INTO articles_hash_mx VALUES (11,  1, 'alamo', 1347);
INSERT INTO articles_hash_mx VALUES (12,  2, 'archiblast', 18185);
INSERT INTO articles_hash_mx VALUES (13,  3, 'aseyev', 2255);
INSERT INTO articles_hash_mx VALUES (14,  4, 'andesite', 19094);
INSERT INTO articles_hash_mx VALUES (15,  5, 'adversa', 3164);
INSERT INTO articles_hash_mx VALUES (16,  6, 'allonym', 2);
INSERT INTO articles_hash_mx VALUES (17,  7, 'auriga', 4073);
INSERT INTO articles_hash_mx VALUES (18,  8, 'assembly', 911);
INSERT INTO articles_hash_mx VALUES (19,  9, 'aubergiste', 4981);
INSERT INTO articles_hash_mx VALUES (20, 10, 'absentness', 1820);
INSERT INTO articles_hash_mx VALUES (21,  1, 'arcading', 5890);
INSERT INTO articles_hash_mx VALUES (22,  2, 'antipope', 2728);
INSERT INTO articles_hash_mx VALUES (23,  3, 'abhorring', 6799);
INSERT INTO articles_hash_mx VALUES (24,  4, 'audacious', 3637);
INSERT INTO articles_hash_mx VALUES (25,  5, 'antehall', 7707);
INSERT INTO articles_hash_mx VALUES (26,  6, 'abington', 4545);
INSERT INTO articles_hash_mx VALUES (27,  7, 'arsenous', 8616);
INSERT INTO articles_hash_mx VALUES (28,  8, 'aerophyte', 5454);
INSERT INTO articles_hash_mx VALUES (29,  9, 'amateur', 9524);
INSERT INTO articles_hash_mx VALUES (30, 10, 'andelee', 6363);
INSERT INTO articles_hash_mx VALUES (31,  1, 'athwartships', 7271);
INSERT INTO articles_hash_mx VALUES (32,  2, 'amazon', 11342);
INSERT INTO articles_hash_mx VALUES (33,  3, 'autochrome', 8180);
INSERT INTO articles_hash_mx VALUES (34,  4, 'amnestied', 12250);
INSERT INTO articles_hash_mx VALUES (35,  5, 'aminate', 9089);
INSERT INTO articles_hash_mx VALUES (36,  6, 'ablation', 13159);
INSERT INTO articles_hash_mx VALUES (37,  7, 'archduchies', 9997);
INSERT INTO articles_hash_mx VALUES (38,  8, 'anatine', 14067);
INSERT INTO articles_hash_mx VALUES (39,  9, 'anchises', 10906);
INSERT INTO articles_hash_mx VALUES (40, 10, 'attemper', 14976);
INSERT INTO articles_hash_mx VALUES (41,  1, 'aznavour', 11814);
INSERT INTO articles_hash_mx VALUES (42,  2, 'ausable', 15885);
INSERT INTO articles_hash_mx VALUES (43,  3, 'affixal', 12723);
INSERT INTO articles_hash_mx VALUES (44,  4, 'anteport', 16793);
INSERT INTO articles_hash_mx VALUES (45,  5, 'afrasia', 864);
INSERT INTO articles_hash_mx VALUES (46,  6, 'atlanta', 17702);
INSERT INTO articles_hash_mx VALUES (47,  7, 'abeyance', 1772);
INSERT INTO articles_hash_mx VALUES (48,  8, 'alkylic', 18610);
INSERT INTO articles_hash_mx VALUES (49,  9, 'anyone', 2681);
INSERT INTO articles_hash_mx VALUES (50, 10, 'anjanette', 19519);
SET client_min_messages TO 'DEBUG2';
-- insert a single row for the test
INSERT INTO articles_single_shard_hash_mx VALUES (50, 10, 'anjanette', 19519);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 10
-- single-shard tests
-- many of the tests in this file is intended for testing non-fast-path
-- router planner, so we're explicitly disabling it in this file.
-- We've bunch of other tests that triggers fast-path-router
SET citus.enable_fast_path_router_planner TO false;
-- test simple select for a single row
SELECT * FROM articles_hash_mx WHERE author_id = 10 AND id = 50;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 10
 id | author_id |   title   | word_count
---------------------------------------------------------------------
 50 |        10 | anjanette |      19519
(1 row)

-- get all titles by a single author
SELECT title FROM articles_hash_mx WHERE author_id = 10;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 10
   title
---------------------------------------------------------------------
 aggrandize
 absentness
 andelee
 attemper
 anjanette
(5 rows)

-- try ordering them by word count
SELECT title, word_count FROM articles_hash_mx
	WHERE author_id = 10
	ORDER BY word_count DESC NULLS LAST;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 10
   title    | word_count
---------------------------------------------------------------------
 anjanette  |      19519
 aggrandize |      17277
 attemper   |      14976
 andelee    |       6363
 absentness |       1820
(5 rows)

-- look at last two articles by an author
SELECT title, id FROM articles_hash_mx
	WHERE author_id = 5
	ORDER BY id
	LIMIT 2;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 5
  title  | id
---------------------------------------------------------------------
 aruru   |  5
 adversa | 15
(2 rows)

-- find all articles by two authors in same shard
-- but plan is not router executable due to order by
SELECT title, author_id FROM articles_hash_mx
	WHERE author_id = 7 OR author_id = 8
	ORDER BY author_id ASC, id;
DEBUG:  Creating router plan
    title    | author_id
---------------------------------------------------------------------
 aseptic     |         7
 auriga      |         7
 arsenous    |         7
 archduchies |         7
 abeyance    |         7
 agatized    |         8
 assembly    |         8
 aerophyte   |         8
 anatine     |         8
 alkylic     |         8
(10 rows)

-- same query is router executable with no order by
SELECT title, author_id FROM articles_hash_mx
	WHERE author_id = 7 OR author_id = 8;
DEBUG:  Creating router plan
    title    | author_id
---------------------------------------------------------------------
 aseptic     |         7
 agatized    |         8
 auriga      |         7
 assembly    |         8
 arsenous    |         7
 aerophyte   |         8
 archduchies |         7
 anatine     |         8
 abeyance    |         7
 alkylic     |         8
(10 rows)

-- add in some grouping expressions, still on same shard
-- having queries unsupported in Citus
SELECT author_id, sum(word_count) AS corpus_size FROM articles_hash_mx
	WHERE author_id = 1 OR author_id = 7 OR author_id = 8 OR author_id = 10
	GROUP BY author_id
	HAVING sum(word_count) > 1000
	ORDER BY sum(word_count) DESC;
DEBUG:  Creating router plan
 author_id | corpus_size
---------------------------------------------------------------------
        10 |       59955
         8 |       55410
         7 |       36756
         1 |       35894
(4 rows)

-- however having clause is supported if it goes to a single shard
SELECT author_id, sum(word_count) AS corpus_size FROM articles_hash_mx
	WHERE author_id = 1
	GROUP BY author_id
	HAVING sum(word_count) > 1000
	ORDER BY sum(word_count) DESC;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 author_id | corpus_size
---------------------------------------------------------------------
         1 |       35894
(1 row)

-- query is a single shard query but can't do shard pruning,
-- not router-plannable due to <= and IN
SELECT * FROM articles_hash_mx WHERE author_id <= 1;
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

SELECT * FROM articles_hash_mx WHERE author_id IN (1, 3);
DEBUG:  Creating router plan
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
  3 |         3 | asternal     |      10480
 11 |         1 | alamo        |       1347
 13 |         3 | aseyev       |       2255
 21 |         1 | arcading     |       5890
 23 |         3 | abhorring    |       6799
 31 |         1 | athwartships |       7271
 33 |         3 | autochrome   |       8180
 41 |         1 | aznavour     |      11814
 43 |         3 | affixal      |      12723
(10 rows)

-- queries with CTEs are supported
WITH first_author AS ( SELECT id FROM articles_hash_mx WHERE author_id = 1)
SELECT * FROM first_author;
DEBUG:  CTE first_author is going to be inlined via distributed planning
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id
---------------------------------------------------------------------
  1
 11
 21
 31
 41
(5 rows)

-- queries with CTEs are supported even if CTE is not referenced inside query
WITH first_author AS ( SELECT id FROM articles_hash_mx WHERE author_id = 1)
SELECT title FROM articles_hash_mx WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
    title
---------------------------------------------------------------------
 arsenous
 alamo
 arcading
 athwartships
 aznavour
(5 rows)

-- two CTE joins are supported if they go to the same worker
WITH id_author AS ( SELECT id, author_id FROM articles_hash_mx WHERE author_id = 1),
id_title AS (SELECT id, title from articles_hash_mx WHERE author_id = 1)
SELECT * FROM id_author, id_title WHERE id_author.id = id_title.id;
DEBUG:  CTE id_author is going to be inlined via distributed planning
DEBUG:  CTE id_title is going to be inlined via distributed planning
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id | id |    title
---------------------------------------------------------------------
  1 |         1 |  1 | arsenous
 11 |         1 | 11 | alamo
 21 |         1 | 21 | arcading
 31 |         1 | 31 | athwartships
 41 |         1 | 41 | aznavour
(5 rows)

WITH id_author AS ( SELECT id, author_id FROM articles_hash_mx WHERE author_id = 1),
id_title AS (SELECT id, title from articles_hash_mx WHERE author_id = 3)
SELECT * FROM id_author, id_title WHERE id_author.id = id_title.id;
DEBUG:  CTE id_author is going to be inlined via distributed planning
DEBUG:  CTE id_title is going to be inlined via distributed planning
DEBUG:  Creating router plan
 id | author_id | id | title
---------------------------------------------------------------------
(0 rows)

-- CTE joins on different workers are supported because they are both planned recursively
WITH id_author AS ( SELECT id, author_id FROM articles_hash_mx WHERE author_id = 1),
id_title AS (SELECT id, title from articles_hash_mx WHERE author_id = 2)
SELECT * FROM id_author, id_title WHERE id_author.id = id_title.id;
DEBUG:  CTE id_author is going to be inlined via distributed planning
DEBUG:  CTE id_title is going to be inlined via distributed planning
DEBUG:  cannot run command which targets multiple shards
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 2
DEBUG:  generating subplan XXX_1 for subquery SELECT id, title FROM public.articles_hash_mx WHERE (author_id OPERATOR(pg_catalog.=) 2)
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT id_author.id, id_author.author_id, id_title.id, id_title.title FROM (SELECT articles_hash_mx.id, articles_hash_mx.author_id FROM public.articles_hash_mx WHERE (articles_hash_mx.author_id OPERATOR(pg_catalog.=) 1)) id_author, (SELECT intermediate_result.id, intermediate_result.title FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(id bigint, title character varying(20))) id_title WHERE (id_author.id OPERATOR(pg_catalog.=) id_title.id)
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id | id | title
---------------------------------------------------------------------
(0 rows)

WITH update_article AS (
    UPDATE articles_hash_mx SET word_count = 11 WHERE id = 1 AND word_count = 10 RETURNING *
)
SELECT coalesce(1,random());
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  generating subplan XXX_1 for CTE update_article: UPDATE public.articles_hash_mx SET word_count = 11 WHERE ((id OPERATOR(pg_catalog.=) 1) AND (word_count OPERATOR(pg_catalog.=) 10)) RETURNING id, author_id, title, word_count
DEBUG:  Creating router plan
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT COALESCE((1)::double precision, random()) AS "coalesce"
DEBUG:  Creating router plan
 coalesce
---------------------------------------------------------------------
        1
(1 row)

WITH update_article AS (
    UPDATE articles_hash_mx SET word_count = 10 WHERE author_id = 1 AND id = 1 AND word_count = 11 RETURNING *
)
SELECT coalesce(1,random());
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 coalesce
---------------------------------------------------------------------
        1
(1 row)

-- recursive CTEs are supported when filtered on partition column
INSERT INTO company_employees_mx values(1, 1, 0);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
INSERT INTO company_employees_mx values(1, 2, 1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
INSERT INTO company_employees_mx values(1, 3, 1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
INSERT INTO company_employees_mx values(1, 4, 2);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
INSERT INTO company_employees_mx values(1, 5, 4);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
INSERT INTO company_employees_mx values(3, 1, 0);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 3
INSERT INTO company_employees_mx values(3, 15, 1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 3
INSERT INTO company_employees_mx values(3, 3, 1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 3
-- find employees at top 2 level within company hierarchy
WITH RECURSIVE hierarchy as (
	SELECT *, 1 AS level
		FROM company_employees_mx
		WHERE company_id = 1 and manager_id = 0
	UNION
	SELECT ce.*, (h.level+1)
		FROM hierarchy h JOIN company_employees_mx ce
			ON (h.employee_id = ce.manager_id AND
				h.company_id = ce.company_id AND
				ce.company_id = 1))
SELECT * FROM hierarchy WHERE LEVEL <= 2;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 company_id | employee_id | manager_id | level
---------------------------------------------------------------------
          1 |           1 |          0 |     1
          1 |           2 |          1 |     2
          1 |           3 |          1 |     2
(3 rows)

-- query becomes not router plannble and gets rejected
-- if filter on company is dropped
WITH RECURSIVE hierarchy as (
	SELECT *, 1 AS level
		FROM company_employees_mx
		WHERE company_id = 1 and manager_id = 0
	UNION
	SELECT ce.*, (h.level+1)
		FROM hierarchy h JOIN company_employees_mx ce
			ON (h.employee_id = ce.manager_id AND
				h.company_id = ce.company_id))
SELECT * FROM hierarchy WHERE LEVEL <= 2;
DEBUG:  Router planner cannot handle multi-shard select queries
ERROR:  recursive CTEs are not supported in distributed queries
-- logically wrong query, query involves different shards
-- from the same table, but still router plannable due to
-- shard being placed on the same worker.
WITH RECURSIVE hierarchy as (
	SELECT *, 1 AS level
		FROM company_employees_mx
		WHERE company_id = 3 and manager_id = 0
	UNION
	SELECT ce.*, (h.level+1)
		FROM hierarchy h JOIN company_employees_mx ce
			ON (h.employee_id = ce.manager_id AND
				h.company_id = ce.company_id AND
				ce.company_id = 2))
SELECT * FROM hierarchy WHERE LEVEL <= 2;
DEBUG:  cannot run command which targets multiple shards
ERROR:  recursive CTEs are not supported in distributed queries
-- grouping sets are supported on single shard
SELECT
	id, substring(title, 2, 1) AS subtitle, count(*)
	FROM articles_hash_mx
	WHERE author_id = 1 or author_id = 3
	GROUP BY GROUPING SETS ((id),(subtitle))
	ORDER BY id, subtitle;
DEBUG:  Creating router plan
 id | subtitle | count
---------------------------------------------------------------------
  1 |          |     1
  3 |          |     1
 11 |          |     1
 13 |          |     1
 21 |          |     1
 23 |          |     1
 31 |          |     1
 33 |          |     1
 41 |          |     1
 43 |          |     1
    | b        |     1
    | f        |     1
    | l        |     1
    | r        |     2
    | s        |     2
    | t        |     1
    | u        |     1
    | z        |     1
(18 rows)

-- grouping sets are not supported on multiple shards
SELECT
	id, substring(title, 2, 1) AS subtitle, count(*)
	FROM articles_hash_mx
	WHERE author_id = 1 or author_id = 2
	GROUP BY GROUPING SETS ((id),(subtitle))
	ORDER BY id, subtitle;
DEBUG:  Router planner cannot handle multi-shard select queries
ERROR:  could not run distributed query with GROUPING SETS, CUBE, or ROLLUP
HINT:  Consider using an equality filter on the distributed table's partition column.
-- queries which involve functions in FROM clause are supported if it goes to a single worker.
SELECT * FROM articles_hash_mx, position('om' in 'Thomas') WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count | position
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572 |        3
 11 |         1 | alamo        |       1347 |        3
 21 |         1 | arcading     |       5890 |        3
 31 |         1 | athwartships |       7271 |        3
 41 |         1 | aznavour     |      11814 |        3
(5 rows)

SELECT * FROM articles_hash_mx, position('om' in 'Thomas') WHERE author_id = 1 or author_id = 3;
DEBUG:  Creating router plan
 id | author_id |    title     | word_count | position
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572 |        3
  3 |         3 | asternal     |      10480 |        3
 11 |         1 | alamo        |       1347 |        3
 13 |         3 | aseyev       |       2255 |        3
 21 |         1 | arcading     |       5890 |        3
 23 |         3 | abhorring    |       6799 |        3
 31 |         1 | athwartships |       7271 |        3
 33 |         3 | autochrome   |       8180 |        3
 41 |         1 | aznavour     |      11814 |        3
 43 |         3 | affixal      |      12723 |        3
(10 rows)

-- they are supported via (sub)query pushdown if multiple workers are involved
SELECT * FROM articles_hash_mx, position('om' in 'Thomas') WHERE author_id = 1 or author_id = 2 ORDER BY 4 DESC, 1 DESC, 2 DESC LIMIT 5;
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  push down of limit count: 5
 id | author_id |   title    | word_count | position
---------------------------------------------------------------------
 12 |         2 | archiblast |      18185 |        3
 42 |         2 | ausable    |      15885 |        3
  2 |         2 | abducing   |      13642 |        3
 41 |         1 | aznavour   |      11814 |        3
 32 |         2 | amazon     |      11342 |        3
(5 rows)

-- subqueries are supported in FROM clause but they are not router plannable
SELECT articles_hash_mx.id,test.word_count
FROM articles_hash_mx, (SELECT id, word_count FROM articles_hash_mx) AS test WHERE test.id = articles_hash_mx.id
ORDER BY test.word_count DESC, articles_hash_mx.id LIMIT 5;
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 id, word_count FROM public.articles_hash_mx
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT articles_hash_mx.id, test.word_count FROM public.articles_hash_mx, (SELECT intermediate_result.id, intermediate_result.word_count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(id bigint, word_count integer)) test WHERE (test.id OPERATOR(pg_catalog.=) articles_hash_mx.id) ORDER BY test.word_count DESC, articles_hash_mx.id LIMIT 5
DEBUG:  Router planner cannot handle multi-shard select queries
DEBUG:  push down of limit count: 5
 id | word_count
---------------------------------------------------------------------
 50 |      19519
 14 |      19094
 48 |      18610
 12 |      18185
 46 |      17702
(5 rows)

SELECT articles_hash_mx.id,test.word_count
FROM articles_hash_mx, (SELECT id, word_count FROM articles_hash_mx) AS test
WHERE test.id = articles_hash_mx.id and articles_hash_mx.author_id = 1
ORDER BY articles_hash_mx.id;
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 id, word_count FROM public.articles_hash_mx
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT articles_hash_mx.id, test.word_count FROM public.articles_hash_mx, (SELECT intermediate_result.id, intermediate_result.word_count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(id bigint, word_count integer)) test WHERE ((test.id OPERATOR(pg_catalog.=) articles_hash_mx.id) AND (articles_hash_mx.author_id OPERATOR(pg_catalog.=) 1)) ORDER BY articles_hash_mx.id
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | word_count
---------------------------------------------------------------------
  1 |       9572
 11 |       1347
 21 |       5890
 31 |       7271
 41 |      11814
(5 rows)

-- subqueries in SELECT clause
SELECT a.title AS name, (SELECT a2.id FROM articles_single_shard_hash_mx a2 WHERE a.id = a2.id  LIMIT 1)
						 AS special_price FROM articles_hash_mx a;
DEBUG:  Router planner cannot handle multi-shard select queries
ERROR:  complex joins are only supported when all distributed tables are co-located and joined on their distribution columns
-- simple lookup query
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- below query hits a single shard, router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 OR author_id = 17;
DEBUG:  Creating router plan
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- below query hits two shards, not router plannable + not router executable
-- handled by real-time executor
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 OR author_id = 18;
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- rename the output columns
SELECT id as article_id, word_count * id as random_value
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 article_id | random_value
---------------------------------------------------------------------
          1 |         9572
         11 |        14817
         21 |       123690
         31 |       225401
         41 |       484374
(5 rows)

-- we can push down co-located joins to a single worker
SELECT a.author_id as first_author, b.word_count as second_word_count
	FROM articles_hash_mx a, articles_hash_mx b
	WHERE a.author_id = 10 and a.author_id = b.author_id
	LIMIT 3;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 10
 first_author | second_word_count
---------------------------------------------------------------------
           10 |             17277
           10 |              1820
           10 |              6363
(3 rows)

-- following join is router plannable since the same worker
-- has both shards
SELECT a.author_id as first_author, b.word_count as second_word_count
	FROM articles_hash_mx a, articles_single_shard_hash_mx b
	WHERE a.author_id = 10 and a.author_id = b.author_id
	LIMIT 3;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 10
 first_author | second_word_count
---------------------------------------------------------------------
           10 |             19519
           10 |             19519
           10 |             19519
(3 rows)

-- following join is not router plannable since there are no
-- workers containing both shards, but will work through recursive
-- planning
SET client_min_messages TO INFO;
WITH single_shard as (SELECT * FROM articles_single_shard_hash_mx)
SELECT a.author_id as first_author, b.word_count as second_word_count
	FROM articles_hash_mx a, single_shard b
	WHERE a.author_id = 2 and a.author_id = b.author_id
	LIMIT 3;
 first_author | second_word_count
---------------------------------------------------------------------
(0 rows)

SET client_min_messages TO DEBUG;
-- single shard select with limit is router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1
	LIMIT 3;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
 11 |         1 | alamo    |       1347
 21 |         1 | arcading |       5890
(3 rows)

-- single shard select with limit + offset is router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1
	LIMIT 2
	OFFSET 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |  title   | word_count
---------------------------------------------------------------------
 11 |         1 | alamo    |       1347
 21 |         1 | arcading |       5890
(2 rows)

-- single shard select with limit + offset + order by is router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1
	ORDER BY id desc
	LIMIT 2
	OFFSET 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
 31 |         1 | athwartships |       7271
 21 |         1 | arcading     |       5890
(2 rows)

-- single shard select with group by on non-partition column is router plannable
SELECT id
	FROM articles_hash_mx
	WHERE author_id = 1
	GROUP BY id
	ORDER BY id;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id
---------------------------------------------------------------------
  1
 11
 21
 31
 41
(5 rows)

-- single shard select with distinct is router plannable
SELECT distinct id
	FROM articles_hash_mx
	WHERE author_id = 1
	ORDER BY id;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id
---------------------------------------------------------------------
  1
 11
 21
 31
 41
(5 rows)

-- single shard aggregate is router plannable
SELECT avg(word_count)
	FROM articles_hash_mx
	WHERE author_id = 2;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 2
        avg
---------------------------------------------------------------------
 12356.400000000000
(1 row)

-- max, min, sum, count are router plannable on single shard
SELECT max(word_count) as max, min(word_count) as min,
	   sum(word_count) as sum, count(word_count) as cnt
	FROM articles_hash_mx
	WHERE author_id = 2;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 2
  max  | min  |  sum  | cnt
---------------------------------------------------------------------
 18185 | 2728 | 61782 |   5
(1 row)

-- queries with aggregates and group by supported on single shard
SELECT max(word_count)
	FROM articles_hash_mx
	WHERE author_id = 1
	GROUP BY author_id;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
  max
---------------------------------------------------------------------
 11814
(1 row)

-- router plannable union queries are supported
SELECT * FROM (
	SELECT * FROM articles_hash_mx WHERE author_id = 1
	UNION
	SELECT * FROM articles_hash_mx WHERE author_id = 3
) AS combination
ORDER BY id;
DEBUG:  Creating router plan
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
  3 |         3 | asternal     |      10480
 11 |         1 | alamo        |       1347
 13 |         3 | aseyev       |       2255
 21 |         1 | arcading     |       5890
 23 |         3 | abhorring    |       6799
 31 |         1 | athwartships |       7271
 33 |         3 | autochrome   |       8180
 41 |         1 | aznavour     |      11814
 43 |         3 | affixal      |      12723
(10 rows)

(SELECT LEFT(title, 1) FROM articles_hash_mx WHERE author_id = 1)
UNION
(SELECT LEFT(title, 1) FROM articles_hash_mx WHERE author_id = 3);
DEBUG:  Creating router plan
 left
---------------------------------------------------------------------
 a
(1 row)

(SELECT LEFT(title, 1) FROM articles_hash_mx WHERE author_id = 1)
INTERSECT
(SELECT LEFT(title, 1) FROM articles_hash_mx WHERE author_id = 3);
DEBUG:  Creating router plan
 left
---------------------------------------------------------------------
 a
(1 row)

SELECT * FROM (
	SELECT LEFT(title, 2) FROM articles_hash_mx WHERE author_id = 1
	EXCEPT
	SELECT LEFT(title, 2) FROM articles_hash_mx WHERE author_id = 3
) AS combination
ORDER BY 1;
DEBUG:  Creating router plan
 left
---------------------------------------------------------------------
 al
 ar
 at
 az
(4 rows)

-- union queries are supported through recursive planning
SET client_min_messages TO DEBUG1;
(SELECT * FROM articles_hash_mx WHERE author_id = 1)
UNION
(SELECT * FROM articles_hash_mx WHERE author_id = 2)
ORDER BY 1,2;
DEBUG:  generating subplan XXX_1 for subquery SELECT id, author_id, title, word_count FROM public.articles_hash_mx WHERE (author_id OPERATOR(pg_catalog.=) 1)
DEBUG:  generating subplan XXX_2 for subquery SELECT id, author_id, title, word_count FROM public.articles_hash_mx WHERE (author_id OPERATOR(pg_catalog.=) 2)
DEBUG:  Plan XXX query after replacing subqueries and CTEs: SELECT intermediate_result.id, intermediate_result.author_id, intermediate_result.title, intermediate_result.word_count FROM read_intermediate_result('XXX_1'::text, 'binary'::citus_copy_format) intermediate_result(id bigint, author_id bigint, title character varying(20), word_count integer) UNION SELECT intermediate_result.id, intermediate_result.author_id, intermediate_result.title, intermediate_result.word_count FROM read_intermediate_result('XXX_2'::text, 'binary'::citus_copy_format) intermediate_result(id bigint, author_id bigint, title character varying(20), word_count integer) ORDER BY 1, 2
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
  2 |         2 | abducing     |      13642
 11 |         1 | alamo        |       1347
 12 |         2 | archiblast   |      18185
 21 |         1 | arcading     |       5890
 22 |         2 | antipope     |       2728
 31 |         1 | athwartships |       7271
 32 |         2 | amazon       |      11342
 41 |         1 | aznavour     |      11814
 42 |         2 | ausable      |      15885
(10 rows)

SELECT * FROM (
	(SELECT * FROM articles_hash_mx WHERE author_id = 1)
	UNION
	(SELECT * FROM articles_hash_mx WHERE author_id = 2)) uu
ORDER BY 1, 2
LIMIT 5;
DEBUG:  push down of limit count: 5
 id | author_id |   title    | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous   |       9572
  2 |         2 | abducing   |      13642
 11 |         1 | alamo      |       1347
 12 |         2 | archiblast |      18185
 21 |         1 | arcading   |       5890
(5 rows)

-- error out for queries with repartition jobs
SELECT *
	FROM articles_hash_mx a, articles_hash_mx b
	WHERE a.id = b.id  AND a.author_id = 1;
ERROR:  the query contains a join that requires repartitioning
HINT:  Set citus.enable_repartition_joins to on to enable repartitioning
-- queries which hit more than 1 shards are not router plannable or executable
-- handled by real-time executor
SELECT *
	FROM articles_hash_mx
	WHERE author_id >= 1 AND author_id <= 3
ORDER BY 1,2,3,4;
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
  2 |         2 | abducing     |      13642
  3 |         3 | asternal     |      10480
 11 |         1 | alamo        |       1347
 12 |         2 | archiblast   |      18185
 13 |         3 | aseyev       |       2255
 21 |         1 | arcading     |       5890
 22 |         2 | antipope     |       2728
 23 |         3 | abhorring    |       6799
 31 |         1 | athwartships |       7271
 32 |         2 | amazon       |      11342
 33 |         3 | autochrome   |       8180
 41 |         1 | aznavour     |      11814
 42 |         2 | ausable      |      15885
 43 |         3 | affixal      |      12723
(15 rows)

-- Test various filtering options for router plannable check
SET client_min_messages to 'DEBUG2';
-- this is definitely single shard
-- and router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 and author_id >= 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- not router plannable due to or
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 or id = 1;
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 and (id = 1 or id = 41);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
 41 |         1 | aznavour |      11814
(2 rows)

-- router plannable
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 and (id = random()::int  * 0);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id | title | word_count
---------------------------------------------------------------------
(0 rows)

-- not router plannable due to function call on the right side
SELECT *
	FROM articles_hash_mx
	WHERE author_id = (random()::int  * 0 + 1);
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- not router plannable due to or
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 or id = 1;
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- router plannable due to abs(-1) getting converted to 1 by postgresql
SELECT *
	FROM articles_hash_mx
	WHERE author_id = abs(-1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- not router plannable due to abs() function
SELECT *
	FROM articles_hash_mx
	WHERE 1 = abs(author_id);
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- not router plannable due to abs() function
SELECT *
	FROM articles_hash_mx
	WHERE author_id = abs(author_id - 2);
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- router plannable, function on different field
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1 and (id = abs(id - 2));
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
(1 row)

-- not router plannable due to is true
SELECT *
	FROM articles_hash_mx
	WHERE (author_id = 1) is true;
DEBUG:  Router planner cannot handle multi-shard select queries
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- router plannable, (boolean expression) = true is collapsed to (boolean expression)
SELECT *
	FROM articles_hash_mx
	WHERE (author_id = 1) = true;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- router plannable, between operator is on another column
SELECT *
	FROM articles_hash_mx
	WHERE (author_id = 1) and id between 0 and 20;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
 11 |         1 | alamo    |       1347
(2 rows)

-- router plannable, partition column expression is and'ed to rest
SELECT *
	FROM articles_hash_mx
	WHERE (author_id = 1) and (id = 1 or id = 31) and title like '%s';
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 31 |         1 | athwartships |       7271
(2 rows)

-- router plannable, order is changed
SELECT *
	FROM articles_hash_mx
	WHERE (id = 1 or id = 31) and title like '%s' and (author_id = 1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 31 |         1 | athwartships |       7271
(2 rows)

-- router plannable
SELECT *
	FROM articles_hash_mx
	WHERE (title like '%s' or title like 'a%') and (author_id = 1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- router plannable
SELECT *
	FROM articles_hash_mx
	WHERE (title like '%s' or title like 'a%') and (author_id = 1) and (word_count < 3000 or word_count > 8000);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
 11 |         1 | alamo    |       1347
 41 |         1 | aznavour |      11814
(3 rows)

-- window functions are supported if query is router plannable
SELECT LAG(title, 1) over (ORDER BY word_count) prev, title, word_count
	FROM articles_hash_mx
	WHERE author_id = 5;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 5
   prev   |  title   | word_count
---------------------------------------------------------------------
          | afrasia  |        864
 afrasia  | adversa  |       3164
 adversa  | antehall |       7707
 antehall | aminate  |       9089
 aminate  | aruru    |      11389
(5 rows)

SELECT LAG(title, 1) over (ORDER BY word_count) prev, title, word_count
	FROM articles_hash_mx
	WHERE author_id = 5
	ORDER BY word_count DESC;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 5
   prev   |  title   | word_count
---------------------------------------------------------------------
 aminate  | aruru    |      11389
 antehall | aminate  |       9089
 adversa  | antehall |       7707
 afrasia  | adversa  |       3164
          | afrasia  |        864
(5 rows)

SELECT id, MIN(id) over (order by word_count)
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | min
---------------------------------------------------------------------
 11 |  11
 21 |  11
 31 |  11
  1 |   1
 41 |   1
(5 rows)

SELECT id, word_count, AVG(word_count) over (order by word_count)
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | word_count |          avg
---------------------------------------------------------------------
 11 |       1347 | 1347.0000000000000000
 21 |       5890 | 3618.5000000000000000
 31 |       7271 | 4836.0000000000000000
  1 |       9572 | 6020.0000000000000000
 41 |      11814 | 7178.8000000000000000
(5 rows)

SELECT word_count, rank() OVER (PARTITION BY author_id ORDER BY word_count)
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 word_count | rank
---------------------------------------------------------------------
       1347 |    1
       5890 |    2
       7271 |    3
       9572 |    4
      11814 |    5
(5 rows)

SELECT id, MIN(id) over (order by word_count)
	FROM articles_hash_mx
	WHERE author_id = 1 or author_id = 2
	ORDER BY 1;
DEBUG:  Router planner cannot handle multi-shard select queries
 id | min
---------------------------------------------------------------------
  1 |   1
  2 |   1
 11 |  11
 12 |   1
 21 |  11
 22 |  11
 31 |  11
 32 |   1
 41 |   1
 42 |   1
(10 rows)

SELECT LAG(title, 1) over (ORDER BY word_count) prev, title, word_count
	FROM articles_hash_mx
	WHERE author_id = 5 or author_id = 2
	ORDER BY 2;
DEBUG:  Router planner cannot handle multi-shard select queries
   prev   |   title    | word_count
---------------------------------------------------------------------
 aruru    | abducing   |      13642
 antipope | adversa    |       3164
          | afrasia    |        864
 aminate  | amazon     |      11342
 antehall | aminate    |       9089
 adversa  | antehall   |       7707
 afrasia  | antipope   |       2728
 ausable  | archiblast |      18185
 amazon   | aruru      |      11389
 abducing | ausable    |      15885
(10 rows)

-- complex query hitting a single shard
SELECT
	count(DISTINCT CASE
			WHEN
				word_count > 100
			THEN
				id
			ELSE
				NULL
			END) as c
	FROM
		articles_hash_mx
	WHERE
		author_id = 5;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 5
 c
---------------------------------------------------------------------
 5
(1 row)

-- same query is not router plannable if hits multiple shards
SELECT
	count(DISTINCT CASE
			WHEN
				word_count > 100
			THEN
				id
			ELSE
				NULL
			END) as c
	FROM
		articles_hash_mx
 	GROUP BY
		author_id
	ORDER BY c;
DEBUG:  Router planner cannot handle multi-shard select queries
 c
---------------------------------------------------------------------
 4
 5
 5
 5
 5
 5
 5
 5
 5
 5
(10 rows)

-- queries inside transactions can be router plannable
BEGIN;
SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1
	ORDER BY id;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

END;
-- cursor queries are router plannable
BEGIN;
DECLARE test_cursor CURSOR FOR
	SELECT *
		FROM articles_hash_mx
		WHERE author_id = 1
		ORDER BY id;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
FETCH test_cursor;
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
(1 row)

FETCH test_cursor;
 id | author_id | title | word_count
---------------------------------------------------------------------
 11 |         1 | alamo |       1347
(1 row)

FETCH BACKWARD test_cursor;
 id | author_id |  title   | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous |       9572
(1 row)

END;
-- queries inside copy can be router plannable
COPY (
	SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1
	ORDER BY id) TO STDOUT;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
1	1	arsenous	9572
11	1	alamo	1347
21	1	arcading	5890
31	1	athwartships	7271
41	1	aznavour	11814
-- table creation queries inside can be router plannable
CREATE TEMP TABLE temp_articles_hash_mx as
	SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1
	ORDER BY id;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
-- router plannable queries may include filter for aggregates
SELECT count(*), count(*) FILTER (WHERE id < 3)
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 count | count
---------------------------------------------------------------------
     5 |     1
(1 row)

-- non-router plannable queries support filters as well
SELECT count(*), count(*) FILTER (WHERE id < 3)
	FROM articles_hash_mx
	WHERE author_id = 1 or author_id = 2;
DEBUG:  Router planner cannot handle multi-shard select queries
 count | count
---------------------------------------------------------------------
    10 |     2
(1 row)

-- prepare queries can be router plannable
PREPARE author_1_articles as
	SELECT *
	FROM articles_hash_mx
	WHERE author_id = 1;
EXECUTE author_1_articles;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- parametric prepare queries can be router plannable
PREPARE author_articles(int) as
	SELECT *
	FROM articles_hash_mx
	WHERE author_id = $1;
EXECUTE author_articles(1);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

-- queries inside plpgsql functions could be router plannable
CREATE OR REPLACE FUNCTION author_articles_max_id() RETURNS int AS $$
DECLARE
  max_id integer;
BEGIN
	SELECT MAX(id) FROM articles_hash_mx ah
		WHERE author_id = 1
		into max_id;
	return max_id;
END;
$$ LANGUAGE plpgsql;
SELECT author_articles_max_id();
DEBUG:  Creating router plan
CONTEXT:  SQL statement "SELECT MAX(id) FROM articles_hash_mx ah
		WHERE author_id = 1"
PL/pgSQL function author_articles_max_id() line 5 at SQL statement
DEBUG:  query has a single distribution column value: 1
CONTEXT:  SQL statement "SELECT MAX(id) FROM articles_hash_mx ah
		WHERE author_id = 1"
PL/pgSQL function author_articles_max_id() line 5 at SQL statement
 author_articles_max_id
---------------------------------------------------------------------
                     41
(1 row)

-- plpgsql function that return query results are not router plannable
CREATE OR REPLACE FUNCTION author_articles_id_word_count() RETURNS TABLE(id bigint, word_count int) AS $$
DECLARE
BEGIN
	RETURN QUERY
		SELECT ah.id, ah.word_count
		FROM articles_hash_mx ah
		WHERE author_id = 1;

END;
$$ LANGUAGE plpgsql;
SELECT * FROM author_articles_id_word_count();
DEBUG:  Creating router plan
CONTEXT:  SQL statement "SELECT ah.id, ah.word_count
		FROM articles_hash_mx ah
		WHERE author_id = 1"
PL/pgSQL function author_articles_id_word_count() line 4 at RETURN QUERY
DEBUG:  query has a single distribution column value: 1
CONTEXT:  SQL statement "SELECT ah.id, ah.word_count
		FROM articles_hash_mx ah
		WHERE author_id = 1"
PL/pgSQL function author_articles_id_word_count() line 4 at RETURN QUERY
 id | word_count
---------------------------------------------------------------------
  1 |       9572
 11 |       1347
 21 |       5890
 31 |       7271
 41 |      11814
(5 rows)

-- materialized views can be created for router plannable queries
CREATE MATERIALIZED VIEW mv_articles_hash_mx AS
	SELECT * FROM articles_hash_mx WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
SELECT * FROM mv_articles_hash_mx;
 id | author_id |    title     | word_count
---------------------------------------------------------------------
  1 |         1 | arsenous     |       9572
 11 |         1 | alamo        |       1347
 21 |         1 | arcading     |       5890
 31 |         1 | athwartships |       7271
 41 |         1 | aznavour     |      11814
(5 rows)

SET client_min_messages to 'INFO';
DROP MATERIALIZED VIEW mv_articles_hash_mx;
SET client_min_messages to 'DEBUG2';
CREATE MATERIALIZED VIEW mv_articles_hash_mx_error AS
	SELECT * FROM articles_hash_mx WHERE author_id in (1,2);
DEBUG:  Router planner cannot handle multi-shard select queries
INSERT INTO articles_hash_mx VALUES (51,  1, 'amateus', 1814);
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
-- verify insert is successfull (not router plannable and executable)
SELECT id
	FROM articles_hash_mx
	WHERE author_id = 1;
DEBUG:  Creating router plan
DEBUG:  query has a single distribution column value: 1
 id
---------------------------------------------------------------------
  1
 11
 21
 31
 41
 51
(6 rows)