Building index from multiple tables for text search

Question

Hallo,
I had a look at how to build a index table to optimize search with Oracle text.
At the moment we are using a JOIN of tables to search for a text in several fields located in different tables.
My question is:
Is it possible to create that index table from several tables?
If yes, can you point me out to any links or give me an example.
So far, all the examples I read were about 1 table only.
Thanks
Elisabeth

Answer 1

The following is an extension of the original example. It uses ctx_ddl.sync_index to synchronize the index and shows the changes in one of the index tables and shows that the query finds the newly synchronized data. It also shows how this only happens when the column that the index is on is updated. In this example, the index is on the dummy column. The first update does not update the dummy column, so the ctx_ddl.sync_index command does not synchronize the new data. The second update does update the related dummy column, so ctx_ddl.sync_index does synchronize the new data. Lastly, I showed what happens to one of the index tables when you rebuild the index. Notice the reduction in rows in the index table after the rebuild process. You could also rebuild online or drop and recreate the index.
SCOTT@10gXE> DROP TABLE addresses
  2  /
Table dropped.
SCOTT@10gXE> DROP TABLE customers
  2  /
Table dropped.
SCOTT@10gXE> CREATE TABLE customers
  2    (customer_id NUMBER,
  3       first_name  VARCHAR2(15),
  4       last_name   VARCHAR2(15),
  5       dummy         VARCHAR2(1),
  6    CONSTRAINT   customers_pk PRIMARY KEY (customer_id))
  7  /
Table created.
SCOTT@10gXE> CREATE TABLE addresses
  2    (customer_id NUMBER,
  3       street         VARCHAR2(15),
  4       city         VARCHAR2(15),
  5       state         VARCHAR2(2),
  6    CONSTRAINT   addresses_fk FOREIGN KEY (customer_id)
  7                REFERENCES customers (customer_id))
  8  /
Table created.
SCOTT@10gXE> GRANT SELECT ON customers TO ctxsys
  2  /
Grant succeeded.
SCOTT@10gXE> GRANT SELECT ON addresses TO ctxsys
  2  /
Grant succeeded.
SCOTT@10gXE> CONNECT CTXSYS/ctxsys_password
Connected.
CTXSYS@10gXE>
CTXSYS@10gXE> CREATE OR REPLACE PROCEDURE concat_cols
  2    (p_rowid IN     ROWID,
  3       p_clob     IN OUT CLOB)
  4  AS
  5    v_clob            CLOB;
  6  BEGIN
  7    FOR c1 IN
  8        (SELECT customer_id, first_name || ' ' || last_name AS data
  9         FROM      scott.customers
10         WHERE  ROWID = p_rowid)
11    LOOP
12        v_clob := v_clob || c1.data;
13        FOR c2 IN
14          (SELECT ' ' || street || ' ' || city || ' ' || state AS data
15           FROM   scott.addresses a
16           WHERE  a.customer_id = c1.customer_id)
17        LOOP
18          v_clob := v_clob || c2.data;
19        END LOOP;
20    END LOOP;
21    p_clob := v_clob;
22  END concat_cols;
23  /
Procedure created.
CTXSYS@10gXE> SHOW ERRORS
No errors.
CTXSYS@10gXE> GRANT EXECUTE ON concat_cols TO scott
  2  /
Grant succeeded.
CTXSYS@10gXE> CONNECT scott/tiger
Connected.
SCOTT@10gXE>
SCOTT@10gXE> EXEC CTX_DDL.DROP_PREFERENCE ('concat_cols_datastore')
PL/SQL procedure successfully completed.
SCOTT@10gXE> BEGIN
  2    CTX_DDL.CREATE_PREFERENCE ('concat_cols_datastore', 'USER_DATASTORE');
  3    CTX_DDL.SET_ATTRIBUTE ('concat_cols_datastore', 'PROCEDURE', 'ctxsys.concat_cols');
  4  END;
  5  /
PL/SQL procedure successfully completed.
SCOTT@10gXE> CREATE INDEX customer_text_idx ON customers (dummy)
  2  INDEXTYPE IS CTXSYS.CONTEXT
  3  PARAMETERS ('datastore concat_cols_datastore')
  4  /
Index created.
SCOTT@10gXE> INSERT INTO customers VALUES (1, 'Bob', 'Smith', NULL)
  2  /
1 row created.
SCOTT@10gXE> INSERT INTO addresses VALUES (1, 'Noplace', 'Nowhere', 'CA')
  2  /
1 row created.
SCOTT@10gXE> INSERT INTO customers VALUES (2, 'Bob', 'Jones', NULL)
  2  /
1 row created.
SCOTT@10gXE> INSERT INTO addresses VALUES (2, 'Smith St.', 'Somewhere', 'CA')
  2  /
1 row created.
SCOTT@10gXE> EXEC CTX_DDL.SYNC_INDEX ('customer_text_idx')
PL/SQL procedure successfully completed.
SCOTT@10gXE> COLUMN   token_text FORMAT A30
SCOTT@10gXE> SELECT   token_text, token_type, token_first, token_last, token_count
  2  FROM     dr$customer_text_idx$i
  3  /
TOKEN_TEXT                     TOKEN_TYPE TOKEN_FIRST TOKEN_LAST TOKEN_COUNT
BOB                                     0           1          2           2
CA                                      0           1          2           2
JONES                                   0           2          2           1
NOPLACE                                 0           1          1           1
NOWHERE                                 0           1          1           1
SMITH                                   0           1          2           2
SOMEWHERE                               0           2          2           1
ST                                      0           2          2           1
8 rows selected.
SCOTT@10gXE> SELECT   c.first_name, c.last_name, a.street, a.city
  2  FROM     customers c, addresses a
  3  WHERE    c.customer_id = a.customer_id
  4  AND      CONTAINS (C.dummy, 'Smith') > 0
  5  /
FIRST_NAME      LAST_NAME       STREET          CITY
Bob             Smith           Noplace         Nowhere
Bob             Jones           Smith St.       Somewhere
SCOTT@10gXE> -- dummy is not updated, so the index is not synchronized:
SCOTT@10gXE> UPDATE   addresses
  2  SET      city = 'Anywhere'
  3  WHERE    city = 'Somewhere'
  4  /
1 row updated.
SCOTT@10gXE> EXEC CTX_DDL.SYNC_INDEX ('customer_text_idx')
PL/SQL procedure successfully completed.
SCOTT@10gXE> SELECT   token_text, token_type, token_first, token_last, token_count
  2  FROM     dr$customer_text_idx$i
  3  /
TOKEN_TEXT                     TOKEN_TYPE TOKEN_FIRST TOKEN_LAST TOKEN_COUNT
BOB                                     0           1          2           2
CA                                      0           1          2           2
JONES                                   0           2          2           1
NOPLACE                                 0           1          1           1
NOWHERE                                 0           1          1           1
SMITH                                   0           1          2           2
SOMEWHERE                               0           2          2           1
ST                                      0           2          2           1
8 rows selected.
SCOTT@10gXE> SELECT   c.first_name, c.last_name, a.street, a.city
  2  FROM     customers c, addresses a
  3  WHERE    c.customer_id = a.customer_id
  4  AND      CONTAINS (C.dummy, 'Anywhere') > 0
  5  /
no rows selected
SCOTT@10gXE> -- once dummy is updated, the index is synchronized:
SCOTT@10gXE> UPDATE   customers
  2  SET      dummy = NULL
  3  WHERE    customer_id = 2
  4  /
1 row updated.
SCOTT@10gXE> EXEC CTX_DDL.SYNC_INDEX ('customer_text_idx')
PL/SQL procedure successfully completed.
SCOTT@10gXE> SELECT   token_text, token_type, token_first, token_last, token_count
  2  FROM     dr$customer_text_idx$i
  3  /
TOKEN_TEXT                     TOKEN_TYPE TOKEN_FIRST TOKEN_LAST TOKEN_COUNT
BOB                                     0           1          2           2
CA                                      0           1          2           2
JONES                                   0           2          2           1
NOPLACE                                 0           1          1           1
NOWHERE                                 0           1          1           1
SMITH                                   0           1          2           2
SOMEWHERE                               0           2          2           1
ST                                      0           2          2           1
ANYWHERE                                0           3          3           1
BOB                                     0           3          3           1
CA                                      0           3          3           1
JONES                                   0           3          3           1
SMITH                                   0           3          3           1
ST                                      0           3          3           1
14 rows selected.
SCOTT@10gXE> SELECT   c.first_name, c.last_name, a.street, a.city
  2  FROM     customers c, addresses a
  3  WHERE    c.customer_id = a.customer_id
  4  AND      CONTAINS (C.dummy, 'Anywhere') > 0
  5  /
FIRST_NAME      LAST_NAME       STREET          CITY
Bob             Jones           Smith St.       Anywhere
SCOTT@10gXE> -- notice the changes if the index is rebuilt or dropped and recreated,
SCOTT@10gXE> ALTER INDEX customer_text_idx REBUILD
  2  /
Index altered.
SCOTT@10gXE> SELECT   token_text, token_type, token_first, token_last, token_count
  2  FROM     dr$customer_text_idx$i
  3  /
TOKEN_TEXT                     TOKEN_TYPE TOKEN_FIRST TOKEN_LAST TOKEN_COUNT
ANYWHERE                                0           2          2           1
BOB                                     0           1          2           2
CA                                      0           1          2           2
JONES                                   0           2          2           1
NOPLACE                                 0           1          1           1
NOWHERE                                 0           1          1           1
SMITH                                   0           1          2           2
ST                                      0           2          2           1
8 rows selected.
SCOTT@10gXE> SELECT   c.first_name, c.last_name, a.street, a.city
  2  FROM     customers c, addresses a
  3  WHERE    c.customer_id = a.customer_id
  4  AND      CONTAINS (C.dummy, 'Anywhere') > 0
  5  /
FIRST_NAME      LAST_NAME       STREET          CITY
Bob             Jones           Smith St.       Anywhere
SCOTT@10gXE>