It looks to me like this code has the potential to give you the same event more than once in the event table each with a different id.

 
 if ($_ =~ /=E-(.*)=event/){
    $event = $1;
    push @event_prepare, $event;
 }
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It would be much simpler to forget using numerical keys and just use the $event itself as the primary key. Use a hash to eliminate duplicates like this ;

 
 if ($_ =~ /=E-(.*)=event/){
    $event_prepare{$1} = 1;
 }
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With regard to the article table, I would use the n value from the filename outputcondord.n.txt as the primary key thus avoiding sorting and synchronising problems as well as making the data in the table more human readable. Your article_event_index would then just need to contain the n value from the filename and the text from the events in that file.

poj