* Add Flat Index Delete
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>

* Fix log
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>

* Fix bitset
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>

* Fix reference
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>

* fix bug
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>

* fix bug
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>

* fix bug
Signed-off-by: Nsahuang <xiaohai.xu@zilliz.com>