Rather than create/store/sort many billion entities, my script creates
these entities dynamically and maintains a hash of the "top 100". As each
entity is created, I search my hash for the entity with "lowest" value,
based on a number of elements in the hash; then "low" element gets replaced
with "new" element. Code looks like:
my $low = 0;
for( my $new=1; $new<=$iSuit; ++$new ) {
my $snew =
sprintf("%4d%4d",$aSuit{$new}{'rescap'},$aSuit{$new}{'resval'});
my $slow =
sprintf("%4d%4d",$aSuit{$low}{'rescap'},$aSuit{$low}{'resval'});
if( $snew lt $slow ) { $low = $new; }
}
I needed to change this code so that 'rescap' and 'resval' are runtime
options and there could be any number of them, so I created an array @f_seq
and rewrote my simple loop as:
my $low = 0;
for( my $new=1; $new<=$iSuit; ++$new ) {
$a=$new; $b=$low;
if( cmpSuits() > 0 ) { $low = $new; }
}
sub cmpSuits {
my $aval=''; map { $aval=$aval.sprintf("%4d",$aSuit{$a}{$_}); } @f_seq;
my $bval=''; map { $bval=$bval.sprintf("%4d",$aSuit{$b}{$_}); } @f_seq;
$bval cmp $aval; # a<b=1 a=b=0 a>b=-1 ... sorts descending
}
I use $a and $b because at the end of my script, aSuit hash is sorted for
output - also using function "cmpSuits". The problem is that my script is
now horribly slower than the original!! Is this because I used "map"? If
so, what should I have used instead?
Running the script on a small test sample from our database, the original
code runs in 85-90 seconds. The modified code using "map", takes 160-165
seconds. Processing of my "real" database took 69 hours on the original
code, but at 80 hours, my modified script is not even half way! I must
find something a bit faster then "map", but more flexible than my original
code.
BTW: archives for this list appear to be broken since Oct22.
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