See also the rather amazing "let's use hashes, but magically with bind" example in the DBI docs, in section "DBI STATEMENT HANDLE OBJECTS" "Statement Handle Methods" under 'bind_columns'. This uses the (most?) efficient way to populate a hash with the next record of data.

  $sth->execute;
  my %row;
  $sth->bind_columns( \( @row{ @{$sth->{NAME_lc} } } ));
  while ($sth->fetch) {
      print "$row{region}: $row{sales}\n";
  }
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Also, have you quantified the amount of data you need to paw through, in kilobytes or megabytes? Perhaps the sheer quantity of data you're moving (perhaps through a network connection?) is many many megabytes?