Dear monks, I am trying to write a script that will identify the presence of certain terms in a large number of entered text messages. I am experiencing time efficieny problems and would like to know if I could have done anything better. The core of the code, which is the slow part, looks virtually like this: ... 
sub slow_match {
  my($hash_ref_1,$hash_ref_2) = @_;

  while ( my($pattern,$high_lvl_id) = each(%hash1) ) {
    my $match = qr/\b$pattern\b/;
    while ( my($text_id,$text) = each(%hash2) ) {
      if ($text =~ $match) {
         $$hash_ref_1{$text_id} .= ':'.$high_lvl_id;
         foreach my $part (split(/\s/,$pattern)) {
            $$hash_ref_2{$text_id} -> {$part} = 0;
         }
       }
     }
   }
}

[download]
... There are in the order of 20,000 texts and 50,000-100,000 patterns, and there is only on average about 1 pattern matching each text. The script runs in roughly 1.5 hours on my server, which I was hoping to improve. Using the qr// did improve it very much, but perhaps it could be even better. Many thanks, Ola

In reply to Efficient regex matching with qr//; Can I do better? by kruppy

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