In the OP and in your reply above, you use the terms "exact" and "case insensitive" in the context of regex matching in a way that leads me to wonder if you understand that case insensitive matching is inherently inexact. E.g.: 

c:\@Work\Perl>perl -wMstrict -le
"my $rx = qr/^data_123$/i;
 print $rx;
 ;;
 for my $s (qw(data_123 DATA_123 dAtA_123  data_123x data_12 nada_123)
+) {
   if ($s =~ $rx) {
     print qq{'exact' match to '$s'};
     }
   else {
     print qq{NO match to '$s'};
     }
   }
"
(?^i:^data_123$)
'exact' match to 'data_123'
'exact' match to 'DATA_123'
'exact' match to 'dAtA_123'
NO match to 'data_123x'
NO match to 'data_12'
NO match to 'nada_123'

[download]

Update: I should have mentioned that the example above was run under Strawberry Perl version 5.14.4.1.

In reply to Re^3: Compiled regular expression using qr by AnomalousMonk
in thread Compiled regular expression using qr by perlbaski

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