use strict ;
use warnings ;

my(%h, %h2, $f, $master, $newmaster, %db) ;
while( <$f> ) {
   @h{@KEYS} = split ;
   $db{$h{KEYFIELD} = { %h } ;

}

while( <$master> ) {
   @h2{@KEYS} = split ;
   @h2{@OTHERKEYS} = @$db{$h2{KEYFIELD}}{@OTHERKEYS} if exists $db{$h2{KEYFIELD}} ;
   print $newmaster join ":", @h2{@ALLKEYS} ;
}
# move new master ontop of oldmaster