You have tin linage table live in production. The table users <timestamp> as the rowkey. You want
to change the existing rowkeys to <userid><timestamp>. Which of the following should you do?

A.
Modify the client application to write to both the old table and a new table while migrating the
old data separately

B.
Use the ALTER table command to modify the rowkeys

C.
Use the ASSIGN command to modify the rowkeys

D.
Add a new column to store the userid

Explanation:
Rowkeys cannot be changed. The only way they can be “changed” in a table is if
the row is deleted and then re-inserted. This is a fairly common question on the HBase dist-list so
it pays to get the rowkeys right the first time (and/or before you’ve inserted a lot of data).
Reference:Rowkey Design