Please run the following statements against the database:
CREATE UNIQUE INDEX C_Warehouse_I1 ON C_Warehouse(w_id);
CREATE UNIQUE INDEX C_District_I1 ON C_District(d_w_id, d_id);
CREATE UNIQUE INDEX C_Customer_I1 ON C_Customer(c_w_id, c_d_id, c_id);
CREATE INDEX C_Customer_I2 ON C_Customer(c_last, c_w_id, c_d_id, c_first);
CREATE UNIQUE INDEX C_New_Order_I1 ON C_New_Order(no_w_id, no_d_id, no_o_id);
CREATE UNIQUE INDEX C_Order_I1 ON C_Order(o_id, o_w_id, o_d_id);
CREATE UNIQUE INDEX C_Order_Line_I1 ON C_Order_Line(ol_o_id, ol_w_id, ol_d_id, ol_number);
CREATE UNIQUE INDEX C_Item_I1 ON C_Item(i_id);
CREATE UNIQUE INDEX C_Stock_I1 ON C_Stock(s_i_id, s_w_id);