Hi, thanks for answer!
I've read article about TWCS, and I don't understand how claim
"When rows reach their TTL (10 minutes here), they turn into tombstones. Our
table defines that tombstones can be purged 1 minute after they were created.If
all rows are created with the same TTL, SSTables will get 100% droppable
tombstones eventually and perform full SSTable deletion instead of purging
tombstones through compaction."
goes with
"Once the major compaction for a time window is completed, no further
compaction of the data will ever occur."
In above example TTL is 10 minutes, but time window is only one. As far as I
understand C* never compacts passed bucket. Does it check tombstones anyway?
On Thursday, January 18, 2018 1:32 PM, Alain RODRIGUEZ <arodr...@gmail.com>
wrote:
I set default_time_to_live for existing table. Does it affect existing data?
No, it sets a default TTL for the future writes (that is no guarantee, as it
can be overwritten in any specific query).
It seems data to be deleted, but after compaction, I don't see any disk space
freed as expected
Indeed tombstones are responsible for tombstones eviction, yet there are some
conditions to respect to be able to remove the tombstones (for consistency
reasons). I detailed this last year, and even though the content is a bit old,
main principles are still true and the tuning options are still relevant.
About deletes and tombstones:
http://thelastpickle.com/blog/2016/07/27/about-deletes-and-tombstones.html
tl;dr: I would give a try to unchecked_tombstone_compaction: true. Maybe also
consider using TWCS because of this "TTL is also ten days on one table and 100
days on other.". But I really recommend you to understand how this all work to
act wisely. My guess can be wrong.
About TWCS: http://thelastpickle.com/blog/2016/12/08/TWCS-part1.html
C*heers,-----------------------Alain Rodriguez - @arodream -
alain@thelastpickle.comFrance / Spain
The Last Pickle - Apache Cassandra Consultinghttp://www.thelastpickle.com
2018-01-18 11:15 GMT+00:00 Vlad <qa23d-...@yahoo.com.invalid>:
Hi,
I set default_time_to_live for existing table. Does it affect existing data?
It seems data to be deleted, but after compaction, I don't see any disk space
freed as expected. Database has data for almost year, GC time is ten days, and
TTL is also ten days on one table and 100 days on other.
Cassandra version 3.11.0
Thanks.
