orcl> create table t1(c1 number, c2 clob);

Table created.

orcl> create index i1 on t1(c1,c2);
create index i1 on t1(c1,c2)
                         *
ERROR at line 1:
ORA-02327: cannot create index on expression with datatype LOB


orcl>

SCOTT@orcl_11gR2> -- table:
SCOTT@orcl_11gR2> create table t1
  2    (v1	  varchar2(20),
  3  	n1	  number,
  4  	c1	  clob,
  5  	all_cols  varchar2(1))
  6  /

Table created.

SCOTT@orcl_11gR2> -- data:
SCOTT@orcl_11gR2> insert all
  2  into t1 values ('test data in v1 col', 1, 'other data in c1 column', null)
  3  into t1 values ('other data in v1 col', 2, 'test data in c1 column', null)
  4  into t1 values ('more data in v1 col', 3, 'more data in c1 column', null)
  5  select * from dual
  6  /

3 rows created.

SCOTT@orcl_11gR2> -- multi_column_datastore that uses all three columns:
SCOTT@orcl_11gR2> begin
  2    ctx_ddl.create_preference ('your_ds', 'multi_column_datastore');
  3    ctx_ddl.set_attribute ('your_ds', 'columns', 'v1, to_char(n1) n1, c1');
  4  end;
  5  /

PL/SQL procedure successfully completed.

SCOTT@orcl_11gR2> -- text index that uses multi_column_datastore:
SCOTT@orcl_11gR2> create index t1_v1_n1_c1_idx on t1 (all_cols)
  2  indextype is ctxsys.context
  3  parameters ('datastore your_ds')
  4  /

Index created.

SCOTT@orcl_11gR2> -- tokens in domain index table resulting from indexing:
SCOTT@orcl_11gR2> select token_text from dr$t1_v1_n1_c1_idx$i
  2  /

TOKEN_TEXT
----------------------------------------------------------------
1
2
3
C1
COL
COLUMN
DATA
MORE
N1
OTHER
TEST
V1

12 rows selected.

SCOTT@orcl_11gR2> -- search for 'test data' in any of the three columns:
SCOTT@orcl_11gR2> column c1 format a30
SCOTT@orcl_11gR2> set autotrace on explain
SCOTT@orcl_11gR2> select * from t1 where contains (all_cols, 'test data') > 0
  2  /

V1                           N1 C1                             A
-------------------- ---------- ------------------------------ -
test data in v1 col           1 other data in c1 column
other data in v1 col          2 test data in c1 column

2 rows selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 772606908

-----------------------------------------------------------------------------------------------
| Id  | Operation                   | Name            | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                 |     1 |  2041 |     4   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| T1              |     1 |  2041 |     4   (0)| 00:00:01 |
|*  2 |   DOMAIN INDEX              | T1_V1_N1_C1_IDX |       |       |     4   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("CTXSYS"."CONTAINS"("ALL_COLS",'test data')>0)

Note
-----
   - dynamic sampling used for this statement (level=2)

SCOTT@orcl_11gR2> -- search for '3' in any of the three columns:
SCOTT@orcl_11gR2> select * from t1 where contains (all_cols, '3') > 0
  2  /

V1                           N1 C1                             A
-------------------- ---------- ------------------------------ -
more data in v1 col           3 more data in c1 column

1 row selected.


Execution Plan
----------------------------------------------------------
Plan hash value: 772606908

-----------------------------------------------------------------------------------------------
| Id  | Operation                   | Name            | Rows  | Bytes | Cost (%CPU)| Time     |
-----------------------------------------------------------------------------------------------
|   0 | SELECT STATEMENT            |                 |     1 |  2041 |     4   (0)| 00:00:01 |
|   1 |  TABLE ACCESS BY INDEX ROWID| T1              |     1 |  2041 |     4   (0)| 00:00:01 |
|*  2 |   DOMAIN INDEX              | T1_V1_N1_C1_IDX |       |       |     4   (0)| 00:00:01 |
-----------------------------------------------------------------------------------------------

Predicate Information (identified by operation id):
---------------------------------------------------

   2 - access("CTXSYS"."CONTAINS"("ALL_COLS",'3')>0)

Note
-----
   - dynamic sampling used for this statement (level=2)

SCOTT@orcl_11gR2>