Thanks for suggestion. I check it and it did not work, unfortunately. The execution never stops and script runs as before, without throwing any exceptions 
$sth->execute(@arguments);
die "$sth->errstr" if (!$sth); # trap errors
die "No rows updated" if ($sth eq '0E0'); # trap no insert/update

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I am wondering, is there any way to specify which column should be used as a key column containing unique IDs? In the original table, I have 8 columns, in which only values in last 2 are always different, as long as the very first index column I've implemented explicitly. The rest very often could have equal values: 
123    SM_Th2_2_K9me3    SM    Th2    2    K9me3    Tbx21-24    6.98
124    SM_Th2_2_K9me3    SM    Th2    2    K9me3    Tbx21-25    9.31
125    SM_Th2_2_K9me3    SM    Th2    2    K9me3    Tbx21-26    5.12

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Could that be that DB driver just overwriting existing rows when executing INSERT?

In reply to Re^2: Perl DBI: problems inserting data to a table by homeveg
in thread Perl DBI: problems inserting data to a table by homeveg

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