Fixed-Length Records

• Searching takes just as long as with variable-length records

• The win is when we want to modify a record

        sub modify_user_data {
          my ($fh, $user, @newdata) = @_;
          unless (find_user($fh, $user)) {
            seek $fh, 0, SEEK_END;      # Move to end of file
          }
          print $fh pack "A8 A5 A13 A20 A18", $user, @newdata;
        }

• Before, modifying was difficult in general

  • The only easy way was to copy the entire file

  • Now modifying in-place is cheap

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Copyright © 2003 M. J. Dominus