text: SET max_parallel_maintenance_workers TO 4;
  SET min_parallel_index_scan_size TO '128kB';
  
  -- Bug #17245: Make sure that we don't totally fail to VACUUM individual indexes that
  -- happen to be below min_parallel_index_scan_size during parallel VACUUM:
  CREATE TABLE parallel_vacuum_table (a int) WITH (autovacuum_enabled = off);
  INSERT INTO parallel_vacuum_table SELECT i from generate_series(1, 10000) i;
  
  -- Parallel VACUUM will never be used unless there are at least two indexes
  -- that exceed min_parallel_index_scan_size.  Create two such indexes, and
  -- a third index that is smaller than min_parallel_index_scan_size.
  CREATE INDEX regular_sized_index ON parallel_vacuum_table(a);
  CREATE INDEX typically_sized_index ON parallel_vacuum_table(a);
  -- Note: vacuum_in_leader_small_index can apply deduplication, making it ~3x
  -- smaller than the other indexes
  CREATE INDEX vacuum_in_leader_small_index ON parallel_vacuum_table((1));
  
  -- Verify (as best we can) that the cost model for parallel VACUUM
  -- will make our VACUUM run in parallel, while always leaving it up to the
  -- parallel leader to handle the vacuum_in_leader_small_index index:
  SELECT EXISTS (
  SELECT 1
  FROM pg_class
  WHERE oid = 'vacuum_in_leader_small_index'::regclass AND
    pg_relation_size(oid) <
    pg_size_bytes(current_setting('min_parallel_index_scan_size'))
  ) as leader_will_handle_small_index;
  SELECT count(*) as trigger_parallel_vacuum_nindexes
  FROM pg_class
  WHERE oid in ('regular_sized_index'::regclass, 'typically_sized_index'::regclass) AND
    pg_relation_size(oid) >=
    pg_size_bytes(current_setting('min_parallel_index_scan_size'));
  
  -- Parallel VACUUM with B-Tree page deletions, ambulkdelete calls:
  DELETE FROM parallel_vacuum_table;
  VACUUM (PARALLEL 4, INDEX_CLEANUP ON) parallel_vacuum_table;
  
  -- Since vacuum_in_leader_small_index uses deduplication, we expect an
  -- assertion failure with bug #17245 (in the absence of bugfix):
  INSERT INTO parallel_vacuum_table SELECT i FROM generate_series(1, 10000) i;
  
  RESET max_parallel_maintenance_workers;
  RESET min_parallel_index_scan_size;
  
  -- Deliberately don't drop table, to get further coverage from tools like
  -- pg_amcheck in some testing scenarios
  