Remember that this is for Cassandra. Cassandra only allows you to sort records by the primary key, so if you want to sort by date, the time has to be part of th

Remember that this is for Cassandra. Cassandra only allows you to sort records by the primary key, so if you want to sort by date, the time has to be part of the primary key while also being unique. So vanilla UUID doesn't work. Some UUIDs can take a time argument, but as the post says, they couldn't use UUIDs anyway, because they are all 128-bit and Twitter is limited for historical reasons to 64.