Head:
 \i /data/rafia.sabih/dss/queries/12.sql
                                       
-----------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------
 Limit  (cost=1001.19..391123.34 rows=1 width=27) (actual time=45511.755..45511.755 rows=1 loops=1)
   ->  GroupAggregate  (cost=1001.19..2731856.24 rows=7 width=27) (actual time=45511.753..45511.753 rows=1 loops=1)
         Group Key: lineitem.l_shipmode
         ->  Gather Merge  (cost=1001.19..2721491.60 rows=592261 width=27) (actual time=7.806..44794.334 rows=311095 loops=1)
               Workers Planned: 4
               Workers Launched: 4
               ->  Nested Loop  (cost=1.13..2649947.55 rows=148065 width=27) (actual time=0.342..9071.892 rows=62257 loops=5)
                     ->  Parallel Index Scan using idx_l_shipmode on lineitem  (cost=0.57..2543794.01 rows=148065 width=19) (actual time=0.284.
.7936.015 rows=62257 loops=5)
                           Index Cond: (l_shipmode = ANY ('{"REG AIR",RAIL}'::bpchar[]))
                           Filter: ((l_commitdate < l_receiptdate) AND (l_shipdate < l_commitdate) AND (l_receiptdate >= '1995-01-01'::date) AN
D (l_receiptdate < '1996-01-01 00:00:00'::timestamp without time zone))
                           Rows Removed by Filter: 3368075
                     ->  Index Scan using orders_pkey on orders  (cost=0.56..0.71 rows=1 width=20) (actual time=0.016..0.016 rows=1 loops=31128
5)
                           Index Cond: (o_orderkey = lineitem.l_orderkey)
 Planning time: 1.143 ms
 Execution time: 45522.278 ms
(15 rows)



PATCH:
TPC-H queries:
\i /data/rafia.sabih/dss/queries/12.sql
                                                                                                      QUERY PLAN                               
                                                                        
-----------------------------------------------------------------------------------------------------------------------------------------------
------------------------------------------------------------------------
 Limit  (cost=1001.19..391123.34 rows=1 width=27) (actual time=14427.289..14427.290 rows=1 loops=1)
   ->  GroupAggregate  (cost=1001.19..2731856.24 rows=7 width=27) (actual time=14427.287..14427.287 rows=1 loops=1)
         Group Key: lineitem.l_shipmode
         ->  Gather Merge  (cost=1001.19..2721491.60 rows=592261 width=27) (actual time=8.656..13469.925 rows=311095 loops=1)
               Workers Planned: 4
               Workers Launched: 4
               ->  Nested Loop  (cost=1.13..2649947.55 rows=148065 width=27) (actual time=0.418..14050.843 rows=67321 loops=5)
                     ->  Parallel Index Scan using idx_l_shipmode on lineitem  (cost=0.57..2543794.01 rows=148065 width=19) (actual time=0.354.
.12291.338 rows=67321 loops=5)
                           Index Cond: (l_shipmode = ANY ('{"REG AIR",RAIL}'::bpchar[]))
                           Filter: ((l_commitdate < l_receiptdate) AND (l_shipdate < l_commitdate) AND (l_receiptdate >= '1995-01-01'::date) AN
D (l_receiptdate < '1996-01-01 00:00:00'::timestamp without time zone))
                           Rows Removed by Filter: 3639282
                     ->  Index Scan using orders_pkey on orders  (cost=0.56..0.71 rows=1 width=20) (actual time=0.023..0.024 rows=1 loops=33660
6)
                           Index Cond: (o_orderkey = lineitem.l_orderkey)
 Planning time: 1.201 ms
 Execution time: 14569.550 ms
(15 rows)