Hi Michael, yes, you should never loose a delete, because there are no real deletes. No matter what version you are using.
btw: There is actually a ticket that builds an optimization on top of that assumption: CASSANDRA-4917. Basically, if TTL>gc_grace then do not create tombstones for expiring-columns. This works because disappear anyway if TTL is over. cheers, Christian On Thu, Jul 25, 2013 at 3:24 PM, Michael Theroux <mthero...@yahoo.com>wrote: > 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 > > >
