Parallel Sequential Scan is Committed!

akretschmer

Datenbank-Guru
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Robert Haas: Parallel Sequential Scan is Committed!

It works!

Code:
postgres=# set max_parallel_degree = 0;
SET
postgres=# explain analyse select * from foo where val = .4678;
  QUERY PLAN
------------------------------------------------------------------------------------------------------
 Seq Scan on foo  (cost=0.00..17402.00 rows=1 width=12) (actual time=200.679..200.679 rows=0 loops=1)
  Filter: (val = '0.4678'::double precision)
  Rows Removed by Filter: 1000000
 Planning time: 0.072 ms
 Execution time: 200.700 ms
(5 rows)

postgres=# set max_parallel_degree = 2;
SET
postgres=# explain analyse select * from foo where val = .4678;
  QUERY PLAN
-------------------------------------------------------------------------------------------------------------------
 Gather  (cost=1000.00..7960.90 rows=1 width=12) (actual time=84.540..84.540 rows=0 loops=1)
  Number of Workers: 2
  ->  Parallel Seq Scan on foo  (cost=0.00..6960.80 rows=1 width=12) (actual time=52.078..350.967 rows=0 loops=1)
  Filter: (val = '0.4678'::double precision)
  Rows Removed by Filter: 1606084
 Planning time: 0.075 ms
 Execution time: 85.780 ms
(7 rows)

Geile Sache ;-)
 
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