QUERY PLAN        
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 Group  (cost=255656.36..267058.01 rows=912132 width=52) (actual time=368.261..425.734 rows=1082 loops=1)
   ->  Sort  (cost=255656.36..257936.69 rows=912132 width=52) (actual time=368.247..392.925 rows=15360 loops=1)
         Sort Key: ("substring"((a.cod_cta)::text, 1, 8)), b.des_cta
         Sort Method:  external merge  Disk: 1096kB
         ->  Hash Join  (cost=678.38..106119.39 rows=912132 width=52) (actual time=86.187..251.804 rows=15360 loops=1)
               Hash Cond: ((b.cod_cta)::text = "substring"((a.cod_cta)::text, 1, 8))
               ->  Seq Scan on cuentas b  (cost=0.00..463.94 rows=23394 width=52) (actual time=0.035..15.945 rows=23394 loops=1)
               ->  Hash  (cost=580.91..580.91 rows=7798 width=21) (actual time=85.999..85.999 rows=20348 loops=1)
                     ->  Seq Scan on cuentas a  (cost=0.00..580.91 rows=7798 width=21) (actual time=0.022..33.218 rows=20348 loops=1)
                           Filter: (length(cod_cta) > 8)
 Total runtime: 437.343 ms
(11 rows)