0 - 4 of 4 tags for row count

As far as i know, since TD 13, CI is used for "select count(*) from table x" instead of full table scan. But from the manual, 
CI stores below information , But i do not undertand how TD get the row count from below information ?

Hi All,
We keep 3 months of historic data. Is it possible to get the row count of a table on any previous date?
The date might be 1,2 or 3 months old.
I can get the size of the table but is there any method to get row count?

Hi All,
Please help me, we recently implemented new production box which is replica of old production box
now our management want to compare the tables and row count on old and new boxes for each database.
what is the best way to do this.

I noticed that the statement.executeUpdate() method returns int data type , which conforms to JDBC standard. However, here is the question: it is Teradata!!! the affected row count can easily blow away the integer range. How to deal with such issue?