Hello, Quick question on Cassandra, TTLs, tombstones, and GC grace. If we have a column family whose only mechanism of deleting columns is utilizing TTLs, is repair really necessary to make tombstones consistent, and therefore would it be safe to set the gc grace period of the column family to a very low value?
I ask because of this blog post based on Cassandra .7: http://www.datastax.com/dev/blog/whats-new-cassandra-07-expiring-columns. "The first time the expired column is compacted, it is transformed into a tombstone. This transformation frees some disk space: the size of the value of the expired column. From that moment on, the column is a normal tombstone and follows the tombstone rules: it will be totally removed by compaction (including minor ones in most cases since Cassandra 0.6.6) after GCGraceSeconds." Since tombstones are not written using a replicated write, but instead written during compaction, theoretically, it shouldn't be possible to lose a tombstone? Or is this blog post inaccurate for later versions of cassandra? We are using cassandra 1.1.11. Thanks, -Mike
