Originally posted by SANJAY_G
You do not need to rebuild indexes after analyzing table. Try analyzing indexes also. or..
May be your queries work better in Rule based optimizer. If you delete statistics the queries will use RBO again.

Sanjay
Thanks Sanjay. Exactly I did the same. Now performance is back to normal. And it is fine.

One more Doubt, Which analyze table option Estimate/Compute is the best? If I use estimate, will it analyze indexes also? Please guide me. And If I want my queries to use CBO, Do I need to set any parameters? Please advice.

Regards