my $mquery =  "INSERT INTO Search_Results ( search_id, page_id )
                  SELECT ?, P.id
                  FROM Pages P, Documents D, Dirs DI ";

if( $ref_sid ) {
    # constrain search to a previous result set.
    $mquery .= ", Search_Results SR ";
}

$mquery .=     "WHERE MATCH ( P.pgdata ) AGAINST ( ? IN BOOLEAN MODE )
                    AND P.doc_id = D.id
                   AND D.dir_id = DI.id ";

if( $ref_sid ) {
    $mquery .= "AND P.id = SR.page_id AND SR.search_id = ? ";
    push @query_args, $ref_sid;
}