Comment 1 for bug 1149883

My colleagues came up with another approach:

my $filter = "\$event->{QC_Hit}=\$event->{QC_hit} and "
            ."\$event->{Disk_tmp_table}=\$event->{Tmp_table_on_disk} and "
            ."\$event->{Disk_filesort}=\$event->{Filesort_on_disk}";