I don’t think anyone is going to do that. Your question needs a lot of details to answer. It’s like me asking you - Is it colder in winter than it is in Alaska?
Please provide us with more details.
If i want to keep row level security for 20,000 users
it is difficult for me to keep row level security for each and every user.
Is there any other way I can modify the universe by creating view or adding table to set the security login so that each user can see his/her only report.
You don’t need to apply the security for each and every user. Instead, create Groups of users and apply security as per your requirement.
Please have a look at this post for basics.
Do the user ids(same as Busobj userid) along with their data restriction details(any dimension like cost center) are stored in a DB table?
Then you can join this table to a fact or lookup table in the universe using something like
User_table.cost_center= fact_table.cost_center and user_table.userid=@VARIABLE('BOUSER')
This procedure applies if user details are present in a DB table.
There are other options too like ‘enable datasource credentials for Busobj universes’ in the CMC which is used when each DB user(schema) maps on to Busobj user.
The access restrictions in Designer also can be used to apply restrictions on users/groups.