key design

[yutoo yanio <yu...@gmail.com>]

hi
i have a question about key & column design.
in my application we have 3,000,000,000 record in every day
each record contain : user-id, "time stamp", content(max 1KB).
we need to store records for one year, this means we will have about
1,000,000,000,000 after 1 year.
we just search a user-id over rang of "time stamp"
table can design in two way
1.key=userid-timestamp and column:=content
2.key=userid-yyyyMMdd and column:HHmmss=content


in first design we have tall-narrow table but we have very very records, in
second design we have flat-wide table.
which of them have better performance?

thanks.