CREATE SCHEMA am_columnar_join;
SET search_path TO am_columnar_join;
CREATE TABLE users (id int, name text) USING columnar;
INSERT INTO users SELECT a, 'name' || a FROM generate_series(0,30-1) AS a;
CREATE TABLE things (id int, user_id int, name text) USING columnar;
INSERT INTO things SELECT a, a % 30, 'thing' || a FROM generate_series(1,300) AS a;
-- force the nested loop to rescan the table
SET enable_material TO off;
SET enable_hashjoin TO off;
SET enable_mergejoin TO off;
SELECT count(*)
FROM users
JOIN things ON (users.id = things.user_id)
WHERE things.id > 290;
 count
---------------------------------------------------------------------
    10
(1 row)

-- verify the join uses a nested loop to trigger the rescan behaviour
EXPLAIN (COSTS OFF)
SELECT count(*)
FROM users
JOIN things ON (users.id = things.user_id)
WHERE things.id > 299990;
                        QUERY PLAN
---------------------------------------------------------------------
 Aggregate
   ->  Nested Loop
         Join Filter: (users.id = things.user_id)
         ->  Custom Scan (ColumnarScan) on things
               Filter: (id > 299990)
               Columnar Projected Columns: id, user_id
               Columnar Chunk Group Filters: (id > 299990)
         ->  Custom Scan (ColumnarScan) on users
               Columnar Projected Columns: id
(9 rows)

EXPLAIN (COSTS OFF)
SELECT u1.id, u2.id, COUNT(u2.*)
FROM users u1
JOIN users u2 ON (u1.id::text = u2.name)
WHERE u2.id > 299990
GROUP BY u1.id, u2.id;
                        QUERY PLAN
---------------------------------------------------------------------
 HashAggregate
   Group Key: u1.id, u2.id
   ->  Nested Loop
         Join Filter: ((u1.id)::text = u2.name)
         ->  Custom Scan (ColumnarScan) on users u2
               Filter: (id > 299990)
               Columnar Projected Columns: id, name
               Columnar Chunk Group Filters: (id > 299990)
         ->  Custom Scan (ColumnarScan) on users u1
               Columnar Projected Columns: id
(10 rows)

SET client_min_messages TO warning;
DROP SCHEMA am_columnar_join CASCADE;