database - Non spatial indexes in Oracle -

i'm trying create non-spatial index on 2 columns, 1 of geometry column (sdo_geometry). appears documentation possible i'm unable create one.

an excerpt oracle documentation:

for each spatial column in non-spatial index except point columns, column prefix length must specified. (this same requirement indexed blob columns.) prefix length given in bytes.

here's query i'm trying execute create index:

create index multiple_column_index on testdb (id, shape) tablespace test; 

the shape column geometry column here. error i'm receiving is:

sql error: ora-02327: cannot create index on expression datatype adt 02327. 00000 -  "cannot create index on expression datatype %s" *cause:    attempt made create index on non-indexable        expression. *action:   change column datatype or not create index on        expression datatype 1 of  varray, nested table, object,        lob, or  ref. 

i've not applied column prefix here couldn't find documentation explains usage.

there's no way index spatial column part of b-tree index. if have spatial column on 1 of tables — have create spatial domain index on column, in order use spatial functions.

there's no other way index columns.

spatial domain indexes pretty complex - got many interesting options when creating it. 1 can achieve great performance configuring (and using) indexes correctly.