What is the definition of your sub _compare?
(incomplete code cannot possibly demonstrate the problem)

Use the find_dup method to see if there are any duplicates.
(change the format of your values to help you out here, or just forget the whole R_DUP thing, and do something with the keys like some_key_part_1, some_key_part_2 ...)

Here is an example adapted from the DB_File documentation to show you a neat little trick 

use strict ;
    use DB_File ;


    use vars qw( $x %h ) ;

    # Enable duplicate records
    $DB_BTREE->{'flags'} = R_DUP ;

    $x = tie %h, "DB_File", undef, O_RDWR|O_CREAT, 0640, $DB_BTREE 
        or die "Cannot open $filename: $!\n";

        $h{'Wall'} = 'only once';
        $h{'Smith'} = 'more than once';
        $h{'Smith'} = 'more than twice';
        $h{'Smith'} = 'three times';

    my $cnt  = $x->get_dup("Wall") ;
    print "Wall occurred $cnt times\n" ;
    my %hash = $x->get_dup("Wall", 1) ;
    print "Larry is there\n" if $hash{'Larry'} ;
    print "There are $hash{'Brick'} Brick Walls\n" ;
    my @list = sort $x->get_dup("Wall") ;
    print "Wall =>      [@list]\n" ;
    @list = $x->get_dup("Smith") ;
    print "Smith =>     [@list]\n" ;


    @list = $x->get_dup("Dog") ;
    print "Dog =>       [@list]\n" ;

[download]
particularly interesting is this tidbit 


    $count = $x->get_dup($key) ;
    @list  = $x->get_dup($key) ;
    %list  = $x->get_dup($key, 1) ;

[download]

 

Look ma', I'm on CPAN.

** The Third rule of perl club is a statement of fact: pod is sexy.

In reply to (podmaster) Re: In order traversal of BTREE keys where not all keys have duplicate values (using DB_File) by PodMaster
in thread In order traversal of BTREE keys where not all keys have duplicate values (using DB_File) by stajich

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