Maybe tombstones ? Do you issue a lot of DELETE statements ? Or do you re-insert in the same partition with different TTL values ?
On Sat, Mar 5, 2016 at 7:16 PM, Tom van den Berge <t...@drillster.com> wrote: > I don't think compression can be the cause of the difference, because of > two reasons: > > 1) The partition size I calculated myself (3 MB) is the uncompressed size, > and so is the reported size (2.3 GB) > > 2) The difference is simply way too big to be explained by compression, > even if the calculated size would have been the compressed size. The > compression would be 0.125% of the original, which is not realistic. In the > logs, I can see that the typical compression that is achieved for this > table is around 80% of the original. > > Tom > > On Fri, Mar 4, 2016 at 9:48 PM, Robert Coli <rc...@eventbrite.com> wrote: > >> On Fri, Mar 4, 2016 at 5:56 AM, Tom van den Berge <t...@drillster.com> >> wrote: >> >>> Compacting large partition >>> drillster/subscriberstats:rqtPewK-1chi0JSO595u-Q (1,470,058,292 bytes) >>> >>> This means that this single partition is about 1.4GB large. This is much >>> larger that it can possibly be, because of two reasons: >>> 1) the partition has appr. 50K rows, each roughly 62 bytes = ~3 MB >>> 2) the entire table consumes appr. 500MB of disk space on the node >>> containing the partition (including snapshots) >>> >>> Furthermore, nodetool cfstats tells me this: >>> Space used (live): 253,928,111 >>> Space used (total): 253,928,111 >>> Compacted partition maximum bytes: 2,395,318,855 >>> The space used seem to match the actual size (excl. snapshots), but the >>> Compacted partition maximum bytes (2,3 GB) seems to be far higher than >>> possible. Does anyone know how it is possible that Cassandra reports such >>> unlikely sizes? >>> >> >> Compression is enabled by default, and compaction reports the >> uncompressed size. >> >> =Rob >> >> > > > > -- > Tom van den Berge > Lead Software Engineer > > [image: Drillster] > > Middenburcht 136 > 3452 MT Vleuten > Netherlands +31 30 755 53 30 > www.drillster.com > > [image: Follow us on Facebook] Follow us on Facebook > <https://www.facebook.com/Drillster> >
