Parallel Sequential Scan

Giriş

Sequential Scan gibidir. Sadece birden fazla worker tarafından gerçekleştirilir

Örnek

Şöyle yaparız. Tabloda Index olmadığı için Full Table Scan yapılıyor

CREATE TABLE t1 (
    a   int,
    b   int
);
test=# explain analyze select count(*) from t1 where a=9999;
                                                          QUERY PLAN
------------------------------------------------------------------------------------------------------------------------------
 Finalize Aggregate  (cost=10633.65..10633.66 rows=1 width=8) (actual time=43.930..47.172 rows=1 loops=1)
   ->  Gather  (cost=10633.44..10633.65 rows=2 width=8) (actual time=43.766..47.164 rows=3 loops=1)
         Workers Planned: 2
         Workers Launched: 2
         ->  Partial Aggregate  (cost=9633.44..9633.45 rows=1 width=8) (actual time=34.394..34.395 rows=1 loops=3)
               ->  Parallel Seq Scan on t1  (cost=0.00..9633.33 rows=42 width=0) (actual time=34.373..34.385 rows=33 loops=3)
                     Filter: (a = 9999)
                     Rows Removed by Filter: 333300
 Planning Time: 0.313 ms
 Execution Time: 47.250 ms
(10 rows)