Lightweight Databases

Indexing Revisited

A typical use:

        use DB_File;
        tie %by_name, 'DB_File', "./pw_aux", O_CREAT|O_RDWR, 0666
          or die $!;
        open PASSWD, "<", "/etc/passwd" or die $!;

        make_index(\*PASSWD, \%by_name, 
                   sub { (split /:/, $_[0], 2)[0] },
                  );

The key function here takes a password file line and extracts the username
We only need to call make_index once
- (Until the password file changes)
After that, we can get as many fast lookups as we want:

        print find(\*PASSWD, \%by_name, "mjd");

     mjd:x:119:100:Mark Jason Dominus:/home/mjd:/bin/bash