DO
$d$
BEGIN
if mycon =any(dblink_connection()) then
    ----ono uzhe est
else
     PERFORM dblink_connect('mycon','host=10.10.10.10 dbname=mydb port=5432 user=postgres password=pwd'::text);
end if;
PERFORM dblink_exec('mycon','INSERT INTO my_table(f1) VALUES (1);'::text);
PERFORM dblink_disconnect('mycon'); 
END;	
$d$

DO
$d$
BEGIN
PERFORM dblink_connect('mycon','host=10.10.10.10 dbname=mydb port=5432 user=postgres password=pwd'::text);
PERFORM dblink_exec('mycon','INSERT INTO my_table(f1) VALUES (1);'::text);


EXCEPTION WHEN others THEN RAISE NOTICE 'ERROR % SQLSTATE: % %', clock_timestamp(),SQLSTATE,SQLERRM;


PERFORM dblink_disconnect('mycon'); 
END;	
$d$