public void Exec_qry_bgn(Rndm_qry_itm qry_itm) {
    this.qry_itm = qry_itm;

    qry_idx = qry_tbl.Select_by_key(qry_itm.Qry_key());
    if (qry_idx == -1) qry_idx = ++qry_idx_max;
    else {
      // delete all
      qry_tbl.Delete_by_qry_idx(qry_idx);
      rng_tbl.Delete_by_qry_idx(qry_idx);
      seq_tbl.Delete_by_qry_idx(qry_idx);
    }

    rng_idx = seq_in_rng = seq_in_qry = 0;
    rng_stmt = rng_tbl.Insert_stmt();
    seq_stmt = seq_tbl.Insert_stmt();
  }
  public void Split__trg__nth__rls(Split_ctx ctx, Db_conn trg_conn) {
    // make rndm_rng and add
    Rndm_rng_itm rng_itm = bldr.Exec_rng_end_or_null();
    if (rng_itm == null) return;
    Rndm_rng_tbl rng_tbl = new Rndm_rng_tbl(trg_conn);
    rng_tbl.Create_tbl();
    Db_stmt rng_stmt = rng_tbl.Insert_stmt();
    rng_tbl.Insert(
        rng_stmt, rng_itm.Mgr_idx(), rng_itm.Rng_idx(), rng_itm.Seq_bgn(), rng_itm.Seq_end());
    rng_stmt.Rls();
    bldr.Conn().Txn_end();

    // make rndm_seq and bulk copy
    Rndm_seq_tbl seq_tbl = new Rndm_seq_tbl(trg_conn);
    seq_tbl.Create_tbl();
    Split_tbl_.Bld_insert_by_select(tmp_bfr, seq_tbl.Tbl_name(), seq_tbl.Flds());
    tmp_bfr.Add_str_u8_fmt(
        "WHERE {0} = {1} AND {2} = {3}",
        seq_tbl.Fld__qry_idx(), bldr.Qry_idx(), seq_tbl.Fld__rng_idx(), bldr.Rng_idx());
    attach_mgr.Conn_main_(trg_conn).Conn_links_(new Db_attach_itm("src_db", bldr.Conn()));
    attach_mgr.Exec_sql(tmp_bfr.To_str_and_clear());
    //			bldr.Conn().Txn_bgn("rndm");
  }
 public void Exec_seq_itm(int page_id) {
   seq_tbl.Insert(seq_stmt, qry_idx, rng_idx, seq_in_rng, page_id);
   ++seq_in_qry;
   ++seq_in_rng;
 }