Getting all the values under one attribute i.e., column in Dynamo DB?

In my usecase, I have stored details in my table "customer_table" having only hash key as "customer_id" and hash and range global secondary index.

In this table I stored 100 customer id's under "customer_id" attribute , 100 customer names under "customer_name" attribute like this some more attributes.

Now, I need to get all the customer id's and customer names that are stored in the table.

How can i get it? Please explain me and provide some sample java code.

Thanks in advance!!