It's as easy to process a text file line-by-line as it is to suck it into an array first. And line-by-line is more memory friendly. You'll find examples of the line-by-line idiom in nearly every Perl book you may chance to pick up.

Try something like this (and note the extra error handling):

  my $sth = $dbh->prepare(<<"SQL");
  INSERT INTO main (operations,seconds,usr,sys,cpu,tests)
  VALUE (?,?,?,?,?,?)
  SQL

  open(IN, "<$input_file") or die "$input_file: $!";
  while ( <IN> ) {
      chomp;        # remove the trailing \n
      my($operation, $seconds, $usr, $sys, $cpu, $tests) =
          split;

      $sth->execute($operation,$seconds,$usr,$sys,$cpu,$tests);
  }

  close(IN);
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To get SQL errors reported, use {RaiseError => 1} when you make the connection. See the DBI doc for details.