1. Cassandra is quicker than postgre and have lower change to lose data. Cassandra doesn‘t have foreign keys and etcs, so that it‘s quicker on writes.
2. Everything in cassandra is a write. Insert/update/delete is also write.
3. Setting a column to null/ deleting a column will create a tomestone; Deleting a row/primary key/partitio will create a tomestone
4. Could adjust tombstone_warn_threshold and tombstone_failure_threshold in cassandra.yaml.
5. Could adjust gc_grace_seconds when creating table to specify when
6. Hitting tombstone limit only happens per query.
Cassandra Issue with Tombstone
原文：http://www.cnblogs.com/codingforum/p/6275832.html