Malay, I almost forgot to thank you. Thanks a ton.

The following links have more information about this hidden parameter. It's a bug kind.0

http://blogs.oracle.com/theshortensp...le_parame.html

https://support.oracle.com/CSP/main/...tFamily=Oracle

Description of this parameter:
PARM_NAME CURRENT_VAL DEFAULT_VAL DESCR
-------------------- ------------ ------------ ------------------------------------------------------------
_b_tree_bitmap_plans TRUE TRUE enable the use of bitmap plans for tables w. only B-tree ind
exes

SQL> select distinct index_type from dba_indexes;

INDEX_TYPE
---------------------------
CLUSTER
DOMAIN
FUNCTION-BASED NORMAL
IOT - TOP
LOB
NORMAL

6 rows selected.

There is no bitmap index. So, I think that I am on the right track.