seblec:

To be honest, I would normally do it in the SQL, letting it do the grunt work of grouping the data, finding the max and sum:

select category||type as grp, max(category) as cat, max(type) as typ,
       sum(quantity) as qty
from table
group by category || type
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On the perl side, I think you're trying to make rowsGroupBy too "smart". Rather than doing one task well, you're trying to make it a jack-of-all trades. I would think that a simple function that would return a list of records with the group-by keys would be a single function I'd use, something like:

sub group_by {
    my ($rows, $group_keys) = @_;
    my @recs=();
    for my $row (@$rows) {
        push @recs, {
            GRP=>join(chr(28),@{$row}{@$group_keys}),
            %$row 
        };
    }
    return @recs;
}
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Similarly, you could write other single-purpose functions to handle MAX and SUM, or use functions from List::Util and List::MoreUtils to do the other jobs.

...roboticus

When your only tool is a hammer, all problems look like your thumb.