Monks,

My question is related to memory requirements for a large number of hashes.

I DP reasonably large arrays of identically structured records. For naming convenience, I use a hash for each record with the field names as the hash keys

For example: 

  my $people = [
    { name => 'fred', age => 25, height => 1.5 },
    { name => 'sally', age => 20, height => 1.4 },
  ];
  for my $person (@$people} {
    print $person->{name},"\n";
  }

[download]

The record structures are much larger, with typically 80-100 fields and about 4K of data. When dealing with datasets where the data is say 60MB, I am seeing memory usage of 600MB - I believe that this is related to the hash algorith and how many buckets are used etc.

I have searched CPAN, but not found anything - I was wondering if there are any magic Tie modules out there that let me pretend that I am working with an Array of Hash, but that are implemented under the hood as an Array of Array - where the fieldname gets efficiently mapped to an index?

Something like: 

  my $people = [
    [ 'fred',  25,    1.5 ],
    [ 'sally', 20,    1.4 ],
  ];

  my $accessor = accessor->new(
     keys => ['name','age','height'],
     data => $people,
   );

  for my $person (@$people} {
    print $person->{name},"\n";
  }

[download]

Thanks in advance,

Jeff

In reply to Array of Hash interface to an Array of Array? by Anonymous Monk

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