Hi Boying, I agree with Vladimir.If compaction is not compacting the two sstables with updates soon, disk space issues will be wasted. For example, if the updates are not closer in time, first update might be in a big table by the time second update is being written in a new small table. STCS wont compact them together soon. Just adding column values with new timestamp shouldnt create any tombstones. But if data is not merged for long, disk space issues may arise. If you are STCS,just yo get an idea about the extent of the problem you can run major compaction and see the amount of disk space created with that( dont do this in production as major compaction has its own side effects). Which compaction strategy are you using? Are these updates done with TTL? Thanks Anuj On Mon, 14 Nov, 2016 at 1:54 PM, Vladimir Yudovin<vla...@winguzone.com> wrote: Hi Boying,
UPDATE write new value with new time stamp. Old value is not tombstone, but remains until compaction. gc_grace_period is not related to this. Best regards, Vladimir Yudovin, Winguzone - Hosted Cloud Cassandra Launch your cluster in minutes. ---- On Mon, 14 Nov 2016 03:02:21 -0500Lu, Boying <boying...@dell.com> wrote ---- Hi, All, Will the Cassandra generates a new tombstone when updating a column by using CQL update statement? And is there any way to get the number of tombstones of a column family since we want to void generating too many tombstones within gc_grace_period? Thanks Boying
