Jonathan Ellis suggested that I bring this issue to the dev mailing list: Cassandra should recommended a default timestamp across all clients libraries.
Many users on IRC are having difficulty when using different clients because different clients are using different timestamps. If you insert with one client, you may not be able to modify the key later with another. The Cassandra website doesn't seem to mention timestamps much, so users get confused when operations fail on certain clients. Here's what different clients are using: 1. Cassandra CLI: Milliseconds since UTC epoch. 2. lazyboy: Seconds since UTC epoch. It used to be seconds since local time epoch. Now it's changing again to microseconds since UTC epoch. 3. driftx's client: Milliseconds since UTC epoch. 4. The example app, Twissandra: Microseconds since UTC epoch. 5. pycassa: Microseconds since UTC epoch. It used to be seconds since local time epoch. 6. The most popular Cassandra Ruby client: Microseconds since UTC epoch. Here's why the default recommended timestamp should be microseconds since UTC epoch: 1. It allows backwards-compatibility. Some people are already using microseconds, so if it suddenly switched to milliseconds, all the timestamps would be smaller, and they'd be unable to insert or remove existing columns. Microsecond timestamps would always be greater than millisecond timestamps, so new operations would work. 2. There exist reasons people would want to use microseconds over milliseconds (finer granularity), but I don't think there are any reasons one would prefer milliseconds over microseconds. 3 (just for me). I just changed pycassa to microseconds, and I'd hate to change it again :( Jonathan Hseu
