I would start here: http://thelastpickle.com/blog/2016/12/08/TWCS-part1.html
Specifically the “Hints and repairs” and “Timestamp overlap” sections might be
of use.
-B
> On Jan 25, 2018, at 11:05 AM, Thakrar, Jayesh <jthak...@conversantmedia.com>
> wrote:
>
> Wondering if I can get some pointers to what's happening here and why
> sstables that I think should be expired are not being dropped.
>
> Here's the table's compaction property - note also set
> "unchecked_tombstone_compaction" to true.
>
> compaction = {'class':
> 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy',
> 'compaction_window_size': '7', 'compaction_window_unit': 'DAYS',
> 'max_threshold': '4', 'min_threshold': '4', 'unchecked_tombstone_compaction':
> 'true'}
>
> We insert data with timestamp and TTL programmatically.
>
> Here's one set of sstable that I expect to be removed:
>
> $ ls -lt *Data.db | tail -5
> -rw-r--r--. 1 vchadoop vchadoop 31245097312 Sep 20 17:16 mc-1308-big-Data.db
> -rw-r--r--. 1 vchadoop vchadoop 31524316252 Sep 19 14:27 mc-1187-big-Data.db
> -rw-r--r--. 1 vchadoop vchadoop 21405216502 Sep 18 14:14 mc-1070-big-Data.db
> -rw-r--r--. 1 vchadoop vchadoop 13609890747 Sep 13 20:53 mc-178-big-Data.db
>
> $ date +%s
> 1516895877
>
> $ date
> Thu Jan 25 15:58:00 UTC 2018
>
> $ sstablemetadata $PWD/mc-130-big-Data.db | head -20
> SSTable:
> /ae/disk1/data/ae/raw_logs_by_user-f58b9960980311e79ac26928246f09c1/mc-130-big
> Partitioner: org.apache.cassandra.dht.Murmur3Partitioner
> Bloom Filter FP chance: 0.010000
> Minimum timestamp: 1496602800000000
> Maximum timestamp: 1498078800000000
> SSTable min local deletion time: 1507924954
> SSTable max local deletion time: 1509400832
> Compressor: org.apache.cassandra.io.compress.LZ4Compressor
> Compression ratio: 0.17430158132352797
> TTL min: 2630598
> TTL max: 4086188
> First token: -9177441867697829836 (key=823134638755651936)
> Last token: 9155171035305804798 (key=395118640769012487)
> minClustringValues: [-1, da, 3, 1498082382078, -9223371818124305448,
> -9223371652504795402, -1]
> maxClustringValues: [61818, tpt, 325, 1496602800000, -4611686088173246790,
> 9223372014135560885, 1]
> Estimated droppable tombstones: 1.1983492967652476
> SSTable Level: 0
> Repaired at: 0
> Replay positions covered: {CommitLogPosition(segmentId=1505171071629,
> position=7157684)=CommitLogPosition(segmentId=1505171075152,
> position=6263269)}
> totalColumnsSet: 111047277
>
