Problems with Clustering

Hallo to everybody!

I have some Problems with clustering tables: There are 3 tables like:

CREATE TABLE tab_a

(id_tab_a INTEGER,

    col_a1 char()
   );

CREATE TABLE tab_b

(id_tab_b INTEGER,

    id_tab_a INTEGER CONSTRAINT FKb1 REFERENCES tab_a (id_tab_a),     id_tab_x INTEGER CONSTRAINT FKb2 REFERENCES tab_x (id_tab_x)    );

CREATE TABLE tab_c

(id_tab_c INTEGER,

    id_tab_a INTEGER CONSTRAINT FKc1 REFERENCES tab_a (id_tab_a),     id_tab_y INTEGER CONSTRAINT FKc2 REFERENCES tab_y (id_tab_y)    );

I now wanted to create a cluster for tab_b with the foreign keys id_tab_a and id_tab_x and another cluster for table tab_c with id_tab_a and id_tab_y.

How can I assign these Clusters to table tab_a?

I tried out to create cluster with cluster-option, but it's just as little possible as to assign two clusters to one table or to assign only a few
columns of a cluster to one table.

So is it possible to cluster these columns in the shown way and - if yes -
how to?

Greetings,
Ingo

remark: I work on ORACLE Server 7.1.4.6 Received on Sat Sep 13 1997 - 00:00:00 CDT