Oracle Text Context index keeps growing. Optimize seems not to be working

Question

Hi,
In my application I needed to search through many varchar columns from differents tables.
So I created a materialized view in which I concatenate those columns, since they exceed the 4000 characters I merged them concatenating the columns with the TO_CLOBS(column1) || TO_CLOB(column)... || TO_CLOB(columnN).
The query is complex, so the refresh is complete on demand for the view. We refresh it every 2 minutes.
The CONTEXT index is created with the sync on commit parameter.
The index then is synchronized every two minutes.
But when we run the optimize index it does not defrag the index. So it keeps growing.
Any idea ?
Thanks, and sorry for my poor english.
Edited by: detryo on 14-mar-2011 11:06

Answer 1

What are you using to determine that the index is fragmented? Can you post a reproducible test case? Please see my test of what you described below, showing that the optimization does defragment the index.
SCOTT@orcl_11gR2> -- table:
SCOTT@orcl_11gR2> create table test_tab
  2    (col1  varchar2 (10),
  3       col2  varchar2 (10))
  4  /
Table created.
SCOTT@orcl_11gR2> -- materialized view:
SCOTT@orcl_11gR2> create materialized view test_mv3
  2  as
  3  select to_clob (col1) || to_clob (col2) clob_col
  4  from   test_tab
  5  /
Materialized view created.
SCOTT@orcl_11gR2> -- index with sync(on commit):
SCOTT@orcl_11gR2> create index test_idx
  2  on test_mv3 (clob_col)
  3  indextype is ctxsys.context
  4  parameters ('sync (on commit)')
  5  /
Index created.
SCOTT@orcl_11gR2> -- inserts, commits, refreshes:
SCOTT@orcl_11gR2> insert into test_tab values ('a', 'b')
  2  /
1 row created.
SCOTT@orcl_11gR2> commit
  2  /
Commit complete.
SCOTT@orcl_11gR2> exec dbms_mview.refresh ('TEST_MV3')
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> insert into test_tab values ('c a', 'b d')
  2  /
1 row created.
SCOTT@orcl_11gR2> commit
  2  /
Commit complete.
SCOTT@orcl_11gR2> exec dbms_mview.refresh ('TEST_MV3')
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> -- query works:
SCOTT@orcl_11gR2> select * from test_mv3
  2  where  contains (clob_col, 'ab') > 0
  3  /
CLOB_COL
ab
c ab d
2 rows selected.
SCOTT@orcl_11gR2> -- fragmented index:
SCOTT@orcl_11gR2> column token_text format a15
SCOTT@orcl_11gR2> select token_text, token_first, token_last, token_count
  2  from   dr$test_idx$i
  3  /
TOKEN_TEXT      TOKEN_FIRST TOKEN_LAST TOKEN_COUNT
AB                        1          1           1
AB                        2          3           2
C                         3          3           1
3 rows selected.
SCOTT@orcl_11gR2> -- optimizatino:
SCOTT@orcl_11gR2> exec ctx_ddl.optimize_index ('TEST_IDX', 'REBUILD')
PL/SQL procedure successfully completed.
SCOTT@orcl_11gR2> -- defragmented index after optimization:
SCOTT@orcl_11gR2> select token_text, token_first, token_last, token_count
  2  from   dr$test_idx$i
  3  /
TOKEN_TEXT      TOKEN_FIRST TOKEN_LAST TOKEN_COUNT
AB                        2          3           2
C                         3          3           1
2 rows selected.
SCOTT@orcl_11gR2>