All valuable info. I'd like to also add that dbh->selectall_arrayref( $Sql ) by default returns a Reference to an Array of References of each row fields stored in an Array, so it's essentially it's a Reference to an Array of References of row-Arrays, thus there is no need to pass extra parameter { Slice => [] }, since that's a default behavior. Only if you want your individual rows be stored in Hashes instead of Arrays do you need to pass { Slice => {} } as a second parameter, so your call would look like this: dbh->selectall_arrayref( $Sql, { Slice => {} } )