Administración de PostgreSQL
EXPLAIN ANALYZE

Limit  (cost=1301.45..1304.14 rows=20)
       (actual time=658.12..659.68 rows=20 loops=1)
  ->  Merge Join  (cost=1301.45..3320.51 rows=15000)
                  (actual time=658.12..659.62 rows=21
                   loops=1)
        ->  Index Scan using primario_pkey on primario
                 (cost=0.00..1543.85 rows=100085)
                 (actual time=50.92..51.95 rows=134
                  loops=1)
        ->  Sort
                 (cost=1301.45..1301.45 rows=15000)
                 (actual time=607.00..607.05 rows=21
                  loops=1)
              ->  Seq Scan on multi
                    (cost=0.00..261.00 rows=15000)
                    (actual time=12.33..201.44
                     rows=15000 loops=1)
Total runtime: 848.50 msec