I implemented your idea with a slight variation (moved the decimal-correction in the numeric data branch and put the check for empty fields in the non-numeric branch: 
        if ($self->datatype->[$_] =~ /^(?:TINYINT|MEDIUMINT|SMALLINT|I
+NT|INTEGER|BIGINT|FLOAT|DOUBLE)$/) {
            $hr_returnvalue->{$CurrentColumnName} = 0 + substr ($texti
+nput, $self->flatfield_start->[$_], $self->flatfield_length->[$_]);# 
+create a numeric value.
            # Decimal-correction
            if ($self->decimals->[$_] > 0 and defined $hr_returnvalue-
+>{$CurrentColumnName}) {
                $hr_returnvalue->{$CurrentColumnName} /= 10**$self->de
+cimals->[$_];
            }
        } else {
            $hr_returnvalue->{$CurrentColumnName} = substr ($textinput
+, $self->flatfield_start->[$_], $self->flatfield_length->[$_]);
            $hr_returnvalue->{$CurrentColumnName} =~ s/^\s*(.*?)\s*$/$
+1/;    # Trim whitespace
            # Fill empty fields with that field's default value, if su
+ch a value is defined
            if ($hr_returnvalue->{$CurrentColumnName} eq "") { 
                if (defined $self->standadefaultard->[$_]) {
                    if ($self->datatype->[$_] =~ /^(?:CHAR|VARCHAR|DAT
+E|TIME|DATETIME)$/) {
                        $hr_returnvalue->{$CurrentColumnName} = sprint
+f ("%s", $self->default->[$_]);
                    } else {
                        $hr_returnvalue->{$CurrentColumnName} = $self-
+>default->[$_];
                    }
                } else {
                    # Remove empty field
                    delete $hr_returnvalue->{$CurrentColumnName};
                }
            } 
        }

[download]
but the idea is sound. Devel::Size now reports the returned data-structure to be 385251506 bytes, which, for some reason is smaller than the data-structure retrieved from the db...I'll have to look at things more closely to figure out why that is.

In reply to Re^2: Reading (the same) data in different ways & memory usage by Neighbour
in thread Reading (the same) data in different ways & memory usage by Neighbour

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