"Subquery Scan on rec (cost=1628601.89..1676580.92 rows=7381 width=41) (actual time=22171.986..23549.079 rows=1236042 loops=1)" " Filter: (rec.mpos = 1)" " Rows Removed by Filter: 228737" " Buffers: shared hit=45 read=1166951" " I/O Timings: read=29.530" " -> WindowAgg (cost=1628601.89..1658127.45 rows=1476278 width=49) (actual time=22171.983..23379.219 rows=1464779 loops=1)" " Buffers: shared hit=45 read=1166951" " I/O Timings: read=29.530" " -> Sort (cost=1628601.89..1632292.58 rows=1476278 width=41) (actual time=22171.963..22484.044 rows=1464779 loops=1)" " Sort Key: receiving_item_delivered_received.serial_no, receiving_item_delivered_received.eventtime DESC" " Sort Method: quicksort Memory: 163589kB" " Buffers: shared hit=45 read=1166951" " I/O Timings: read=29.530" " -> Gather (cost=1000.00..1477331.13 rows=1476278 width=41) (actual time=1.296..10428.060 rows=1464779 loops=1)" " Workers Planned: 2" " Workers Launched: 2" " Buffers: shared hit=39 read=1166951" " I/O Timings: read=29.530" " -> Parallel Seq Scan on receiving_item_delivered_received (cost=0.00..1328703.33 rows=615116 width=41) (actual time=1.262..10150.325 rows=488260 loops=3)" " Filter: (((COALESCE(serial_no, ''::character varying))::text <> ''::text) AND ((eventtype)::text = 'LineItemdetailsReceived'::text) AND ((replenishmenttype)::text = 'DC2SWARRANTY'::text))" " Rows Removed by Filter: 6906258" " Buffers: shared hit=39 read=1166951" " I/O Timings: read=29.530" "Planning Time: 0.375 ms" "Execution Time: 23617.348 ms"
That is doing a lot of reading from disk. What do you have shared_buffers set to? I'd expect better cache hits unless it is quite low or this is a query that differs greatly from the typical work.
Also, did you try adding the index I suggested? That lowest node has 488k rows coming out of it after throwing away 6.9 million. I would expect an index on only eventtype, replenishmenttype to be quite helpful. I don't assume you have tons of rows where serial_no is null.