text: -- (Q21) Suppliers Who Kept Orders Waiting Query
  -- tables: tpch_supplier, tpch_lineitem, tpch_orders, tpch_nation
  /*SELECT
    s_name,
    count(*)  AS numwait
  FROM
    tpch_supplier,
    tpch_lineitem l1,
    tpch_orders,
    tpch_nation
  WHERE
    s_suppkey = l1.l_suppkey
    AND o_orderkey = l1.l_orderkey
    AND o_orderstatus = 'F'
    AND l1.l_receiptdate > l1.l_commitdate
    AND exists(
      SELECT
        *
      FROM
        tpch_lineitem l2
      WHERE
        l2.l_orderkey = l1.l_orderkey
        AND l2.l_suppkey <> l1.l_suppkey
    )
    AND NOT exists(
      SELECT
        *
      FROM
        tpch_lineitem l3
      WHERE
        l3.l_orderkey = l1.l_orderkey
        AND l3.l_suppkey <> l1.l_suppkey
        AND l3.l_receiptdate > l3.l_commitdate
    )
    AND s_nationkey = n_nationkey
    AND n_name = 'SAUDI ARABIA'
  GROUP BY
    s_name
  ORDER BY
    numwait DESC,
    s_name
  LIMIT 100*/
  -- Disabled because of missing EXISTS($query) support
  SELECT count(*)
  FROM tpch_customer