Update taking time because of db file sequential read.

[paragp1981]

Well size of these each tables is around 15-16 GB. So i cant really create
these temp table that will require huge space .
but if you run

select count(1) from tnpostpaid.rtx_jul_aug
where sncode=1 and call_type=1 and xfile_ind='H'
group by r_p_contract_id, r_p_customer_id, rtx_ent_date
it gives

52128446