From https://docs.datastax.com/en/cassandra/3.0/cassandra/dml/dmlAboutDeletes.html
> Cassandra allows you to set a default_time_to_live property for an entire table. Columns and rows marked with regular TTLs are processed as described above; but when a record exceeds the table-level TTL, **Cassandra deletes it immediately, without tombstoning or compaction**. This is also answered in https://stackoverflow.com/a/50060436/3517383 > If a table has default_time_to_live on it then rows that exceed this time limit are **deleted immediately without tombstones being written**. And commented in LastPickle's post About deletes and tombstones ( http://thelastpickle.com/blog/2016/07/27/about-deletes-and-tombstones.html#comment-3949581514 ) > Another clue to explore would be to use the TTL as a default value if that's a good fit. TTLs set at the table level with 'default_time_to_live' **should not generate any tombstone at all in C*3.0+**. Not tested on my hand, but I read about this. I've made the simplest test that I could imagine using `LeveledCompactionStrategy`: CREATE KEYSPACE IF NOT EXISTS temp WITH replication = {'class': 'SimpleStrategy', 'replication_factor': '1'}; CREATE TABLE IF NOT EXISTS temp.test_ttl ( key text, value text, PRIMARY KEY (key) ) WITH compaction = { 'class': 'LeveledCompactionStrategy'} AND default_time_to_live = 180; 1. `INSERT INTO temp.test_ttl (key,value) VALUES ('k1','v1');` 2. `nodetool flush temp` 3. `sstabledump mc-1-big-Data.db` [image: cassandra0.png] 4. wait for 180 seconds (default_time_to_live) 5. `sstabledump mc-1-big-Data.db` [image: cassandra1.png] The tombstone isn't created yet 6. `nodetool compact temp` 7. `sstabledump mc-2-big-Data.db` [image: cassandra2.png] The **tombstone is created** (and not dropped on compaction due to gc_grace_seconds) The test was performed using apache cassandra 3.0.13 >From the example I conclude that isn't true that `default_time_to_live` not require tombstones, at least for version 3.0.13. However this is a very simple test and I'm forcing a major compaction with `nodetool compact` so I may not be recreating the scenario where default_time_to_live magic comes into play. But how would C* delete without tombstones? Why this should be a different scenario to using TTL per insert? This is also asked at stackoverflow <https://stackoverflow.com/questions/52282517/how-default-time-to-live-would-delete-rows-without-tombstones-in-cassandra>
