How to search for a string in another Postgresql : This bellow is result of the two comand Explain select ....
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    Sort  (cost=399301.55..399301.57 rows=6 width=36) (actual
    time=18749.397..18749.398 rows=4 loops=1)
    Sort Key: l_returnflag, l_linestatus
     Sort Method:  quicksort  Memory: 25kB
     ->  HashAggregate  (cost=399301.21..399301.48 rows=6 width=36)
    (actual time=18749.130..18749.143 rows=4 loops=1)"
           ->  Seq Scan on h_lineitem  (cost=0.00..250095.98 rows=5968209
    width=36) (actual time=0.048..8643.529 rows=5996518 loops=1)"
                 Filter: (l_shipdate <= (to_date('1998/12/01'::text,
    'YYYY/MM/DD'::text) - '10 days'::interval day))"
    
    > Total runtime: 18749.680 ms
    > -----------------------------------
    > ---------------------------------- Aggregate  (cost=7922058.70..7922058.71 rows=1 width=16)"   ->  Hash Join 
    > (cost=1899763.92..7922058.69 rows=1 width=16)"
    >         Hash Cond: (h_lineitem.l_partkey = h_part.p_partkey)"
    >         Join Filter: (((h_part.p_brand = 'Brand#13'::bpchar) AND (h_part.p_container = ANY ('{"SM CASE","SM BOX","SM PACK","SM
    > PKG"}'::bpchar[])) AND (h_lineitem.l_quantity >= 4::double precision)
    > AND (h_lineitem.l_quantity <= 14::double precision) AND (h_ (...)"
    >         ->  Seq Scan on h_lineitem  (cost=0.00..235156.84 rows=211094 width=32)"
    >               Filter: ((l_shipmode = ANY ('{AIR,"AIR REG"}'::bpchar[])) AND (l_shipinstruct = 'DELIVER IN
    > PERSON'::bpchar))"
    >         ->  Hash  (cost=1183158.46..1183158.46 rows=35278997 width=33)"
    >               ->  Seq Scan on h_part  (cost=0.00..1183158.46 rows=35278997 width=33)"
    >                     Filter: (p_size >= 1)"

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I need to capture only string cost=399301.55 (for sample 1nd result). The good news is that the string "COST" is always at the beginning (first line) of the
result.
I try fuctions of string manipulation, but not working.

The problem is that the field "cost" is not always in the same
position (see samples). It is necessary to find what your position is
always.

The expected result is :

select (.... )
-----------------
cost=399301  (only this)
