Greetings:
I have 2 large data sets contained in arrays. Respectively, the sets contain about 30,000 and 100,000 elements. The elements each consist of an identifier and a timestamp delimited by a pipe.
example:
Set 1 (@data):
g123|10249875
g948|32004040

Set 2 (@ref):
g123:1|10249870
g123:2|10249875
g123:3|10249871
g984:2|94950595
g984:1|32004040

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My task is to create a list of identifiers from set 2 where the datestamp is not equal to the corresponding stamp in set 1. This is my code: 
foreach $elem(@data){
   ($sub,$max)=split/\|/,$elem;
   @found=grep /^$sub:/,@ref;
   foreach $f(@found){
      ($id,$time)=split/\|/,$f;
      if($time ne $max){
         push @set,$id;
      }
   }
}

[download]
...And the id's I am looking for end up in @set:
@set:
g123:1
g123:3
g984:2

[download]
Sadly, this method is prohibitively slow. I am looking for suggestions on how to make this process more efficient.
Thanks in advance,
Jason

In reply to Large Set Efficiency Question by insensate

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