This was my first inclination as well -- note that you don't have to sort the file first if you do it this way. A potential downside is that you wind up with the entire data structure in memory.

One option to avoid the memory consumption is to use something like DBD::SQLite as mentioned above. Another option (probably slower and bulkier, but not requiring knowing DBI and SQL) might be to use Tie::MLDBM to store that hash on disk as a DB_File rather than in memory. That might wind up being larger than the original text file, but at least it'll be easy to access it again in perl.

Note: if you use Tie::MLDBM, you'll need to extract the array from the hash to a temporary array, push your data to the temporary array, and then store the temporary array back in the hash. Read the pod for more details. E.g.:

# Code not tested - consider it conceptual #
use strict;
use warnings;
use Tie::MLDBM;

tie my %hash, 'Tie::MLDBM', {
     'Serialise' =>  'Storable',
     'Store'     =>  'DB_File'
 }, 'mybighash.dbm', O_CREAT|O_RDWR, 0640 or die $!;

while (<>) {
  chomp;
  my ($id, $data) = /(\d+)\s+(.*)/;
  my $aref = $hash{$id} || [];
  push @{$aref}, $data;
  $hash{$id} = $aref;
}

[download]

Good luck!

-xdg

Code posted by xdg on PerlMonks is public domain. It has no warranties, express or implied. Posted code may not have been tested. Use at your own risk.

In reply to Re: Re: sort large file by xdg
in thread sort large file by Murcia

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