Yon are storing page view data for a large number of Web sites, each of which has many
subdomains (www.example.com, archive.example.com, beta.example.com, etc.) Your reporting
tool needs to retrieve the total number of page views for a given subdomain of a Web site. Which
of the following rowkeys should you use?
The reverse domain name (e.g., com.example.beta)
The domain name followed by the URL
The URL followed by the reverse domain name
Consider a table whose keys are domain names. It makes the most sense to list
them in reverse notation (so “com.jimbojw.www” rather than “www.jimbojw.com”) so that rows
about a subdomain will be near the parent domain row.
Continuing the domain example, the row for the domain “mail.jimbojw.com” would be right next to
the row for “www.jimbojw.com” rather than say “mail.xyz.com” which would happen if the keys
were regular domain notation.
Reference: Understanding HBase and BigTable