As it turns out, CQL gives us a mechanism for finding out when a particular column was last written. This is done using the WRITETIME function. Let's say we're interested in the write timestamps for the e-mail and the location fields in the happycorp user record:
SELECT "email", WRITETIME("email"), "location", WRITETIME("location") FROM "users" WHERE "username" = 'happycorp';
We'll see that Cassandra gives us the write times of each column formatted as microseconds since the UNIX epoch:
Note that the timestamps are different; we initially wrote the email address when we created the happycorp record and later ...
