> > Since STCS does not sort data based on timestamp, your wide partition may > span over multiple SSTables and inside each SSTable, old data (+ > tombstones) may sit on the same partition as newer data.
Should the data be sorted by my time column regardless of the compaction strategy? I didn't think that the column timestamp came into play with respect to sorting. I have been able to review some SSTables with sstablemetadata and I can see that old/expired data is definitely living with live data. On Sun, Jan 29, 2017 at 2:38 PM, DuyHai Doan <doanduy...@gmail.com> wrote: > Ok so give it a try with TWCS. Since STCS does not sort data based on > timestamp, your wide partition may span over multiple SSTables and inside > each SSTable, old data (+ tombstones) may sit on the same partition as > newer data. > > When reading by slice, even if you request for fresh data, Cassandra has > to scan over a lot tombstones to fetch the correct range of data thus your > issue > > On Sun, Jan 29, 2017 at 8:19 PM, John Sanda <john.sa...@gmail.com> wrote: > >> It was with STCS. It was on a 2.x version before TWCS was available. >> >> On Sun, Jan 29, 2017 at 10:58 AM DuyHai Doan <doanduy...@gmail.com> >> wrote: >> >>> Did you get this Overwhelming tombstonne behavior with STCS or with TWCS >>> ? >>> >>> If you're using DTCS, beware of its weird behavior and tricky >>> configuration. >>> >>> On Sun, Jan 29, 2017 at 3:52 PM, John Sanda <john.sa...@gmail.com> >>> wrote: >>> >>> Your partitioning key is text. If you have multiple entries per id you >>> are likely hitting older cells that have expired. Descending only affects >>> how the data is stored on disk, if you have to read the whole partition to >>> find whichever time you are querying for you could potentially hit >>> tombstones in other SSTables that contain the same "id". As mentioned >>> previously, you need to add a time bucket to your partitioning key and >>> definitely use DTCS/TWCS. >>> >>> >>> As I mentioned previously, the UI only queries recent data, e.g., the >>> past hour, past two hours, past day, past week. The UI does not query for >>> anything older than the TTL which is 7 days. My understanding and >>> expectation was that Cassandra would only scan live cells. The UI is a >>> separate application that I do not maintain, so I am not 100% certain about >>> the queries. I have been told that it does not query for anything older >>> than 7 days. >>> >>> On Sun, Jan 29, 2017 at 4:14 AM, kurt greaves <k...@instaclustr.com> >>> wrote: >>> >>> >>> Your partitioning key is text. If you have multiple entries per id you >>> are likely hitting older cells that have expired. Descending only affects >>> how the data is stored on disk, if you have to read the whole partition to >>> find whichever time you are querying for you could potentially hit >>> tombstones in other SSTables that contain the same "id". As mentioned >>> previously, you need to add a time bucket to your partitioning key and >>> definitely use DTCS/TWCS. >>> >>> >>> >>> >>> >>> -- >>> >>> - John >>> >>> >>> >>> >>> >>> >>> >>> > -- - John
