It depends on your yaml settings - in newer versions you can have cassandra only purge repaired tombstones (and ttl’d data is a tombstone)
You can turn that setting off if either is true: 1) you don’t do explicit deletes, you only insert data that’s ttl’d and let it expire naturally, or 2) data resurrected (due to lack of repair before gc grace seconds) is not a problem for you -- Jeff Jirsa > On Oct 19, 2018, at 3:57 AM, "wxn...@zjqunshuo.com" <wxn...@zjqunshuo.com> > wrote: > > > Is the repair not necessary to get data files remove from filesystem ? > The answer is no. IMO, Cassandra will remove sstable files automatically if > it can make sure the sstable files are 100% of tombstones and safe to do > deletion. If you use TWCS and you have only insertion and no update, you > don't need run repair manually. > > -Simon > > From: Caesar, Maik > Date: 2018-10-18 20:30 > To: user@cassandra.apache.org > Subject: RE: TWCS: Repair create new buckets with old data > Hello Simon, > Is the repair not necessary to get data files remove from filesystem ? My > assumption was, that only repaired data will removed after TTL is reached. > > Regards > Maik > > From: wxn...@zjqunshuo.com [mailto:wxn...@zjqunshuo.com] > Sent: Mittwoch, 17. Oktober 2018 09:02 > To: user <user@cassandra.apache.org> > Subject: Re: TWCS: Repair create new buckets with old data > > Hi Maik, > IMO, when using TWCS, you had better not run repair. The behaviour of TWCS is > same with STCS for repair when merging sstables and the result is leaving > sstables spanning multiple time buckets, but maybe I'm wrong. In my use case, > I don't do repair with table using TWCS. > > -Simon > > From: Caesar, Maik > Date: 2018-10-16 17:46 > To: user@cassandra.apache.org > Subject: TWCS: Repair create new buckets with old data > Hallo, > we work with Cassandra version 3.0.9 and have a problem in a table with TWCS. > The command “nodetool repair” create always new files with old data. This > avoid the delete of the old data. > The layout of the Table is following: > cqlsh> desc stat.spa > > CREATE TABLE stat.spa ( > region int, > id int, > date text, > hour int, > zippedjsonstring blob, > PRIMARY KEY ((region, id), date, hour) > ) WITH CLUSTERING ORDER BY (date ASC, hour ASC) > AND bloom_filter_fp_chance = 0.01 > AND caching = {'keys': 'ALL', 'rows_per_partition': 'NONE'} > AND comment = '' > AND compaction = {'class': > 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy', > 'compaction_window_size': '1', 'compaction_window_unit': 'DAYS', > 'max_threshold': '100', 'min_threshold': '4', > 'tombstone_compaction_interval': '86460'} > AND compression = {'chunk_length_in_kb': '64', 'class': > 'org.apache.cassandra.io.compress.LZ4Compressor'} > AND crc_check_chance = 1.0 > AND dclocal_read_repair_chance = 0.0 > AND default_time_to_live = 0 > AND gc_grace_seconds = 864000 > AND max_index_interval = 2048 > AND memtable_flush_period_in_ms = 0 > AND min_index_interval = 128 > AND read_repair_chance = 0.0 > AND speculative_retry = '99PERCENTILE'; > > Actual the oldest data are from 2017/04/15 and will not remove: > > $ for f in *Data.db; do meta=$(sudo sstablemetadata $f); echo -e "Max:" > $(date --date=@$(echo "$meta" | grep Maximum\ time | cut -d" " -f3| cut -c > 1-10) '+%Y/%m/%d %H:%M') "Min:" $(date --date=@$(echo "$meta" | grep Minimum\ > time | cut -d" " -f3| cut -c 1-10) '+%Y/%m/%d %H:%M') $(echo "$meta" | grep > droppable) $(echo "$meta" | grep "Repaired at") ' \t ' $(ls -lh $f | awk > '{print $5" "$6" "$7" "$8" "$9}'); done | sort > Max: 2017/04/15 12:08 Min: 2017/03/31 13:09 Estimated droppable tombstones: > 1.7731048805815162 Repaired at: 1525685601400 42K May 7 19:56 > mc-22922-big-Data.db > Max: 2017/04/17 13:49 Min: 2017/03/31 13:09 Estimated droppable tombstones: > 1.9600207684319835 Repaired at: 1525685601400 116M May 7 13:31 > mc-15096-big-Data.db > Max: 2017/04/21 13:43 Min: 2017/04/15 13:34 Estimated droppable tombstones: > 1.9090909090909092 Repaired at: 1525685601400 11K May 7 19:56 > mc-22921-big-Data.db > Max: 2017/05/23 21:45 Min: 2017/04/21 14:00 Estimated droppable tombstones: > 1.8360655737704918 Repaired at: 1525685601400 21M May 7 19:56 > mc-22919-big-Data.db > Max: 2017/06/12 15:19 Min: 2017/04/25 14:45 Estimated droppable tombstones: > 1.8091397849462365 Repaired at: 1525685601400 19M May 7 14:36 > mc-17095-big-Data.db > Max: 2017/06/15 15:26 Min: 2017/05/10 14:37 Estimated droppable tombstones: > 1.76536312849162 Repaired at: 1529612605539 9.3M Jun 21 22:31 > mc-25372-big-Data.db > … > > After a „nodetool repair“ run, a new big data file is created that include > old data from 2017/07/31. > > Max: 2018/07/27 18:10 Min: 2017/03/31 13:13 Estimated droppable tombstones: > 0.08392555471691247 Repaired at: 0 11G Sep 11 22:02 > mc-39281-big-Data.db > … > Max: 2018/08/16 18:18 Min: 2018/08/06 12:19 Estimated droppable tombstones: > 0.0 Repaired at: 1534525730510 123M Aug 17 23:46 mc-36847-big-Data.db > Max: 2018/08/17 19:20 Min: 2017/07/31 12:04 Estimated droppable tombstones: > 0.03385963490004347 Repaired at: 0 11G Sep 11 21:43 > mc-39265-big-Data.db > Max: 2018/08/17 19:20 Min: 2018/07/24 12:33 Estimated droppable tombstones: > 0.0 Repaired at: 1534525730510 135M Sep 11 21:44 mc-39270-big-Data.db > … > Max: 2018/09/06 17:30 Min: 2018/08/28 12:17 Estimated droppable tombstones: > 0.0 Repaired at: 1536690786879 129M Sep 11 21:10 mc-39238-big-Data.db > Max: 2018/09/07 18:22 Min: 2017/04/23 12:48 Estimated droppable tombstones: > 0.1548442441468401 Repaired at: 0 8.0G Sep 11 21:33 mc-39258-big-Data.db > Max: 2018/09/07 18:22 Min: 2018/09/07 12:15 Estimated droppable tombstones: > 0.0 Repaired at: 1536690786879 72M Sep 11 21:34 mc-39262-big-Data.db > Max: 2018/09/08 18:20 Min: 2018/08/22 12:17 Estimated droppable tombstones: > 0.0 Repaired at: 0 2.8G Sep 11 21:47 mc-39272-big-Data.db > > The tool sstableexpiredblockers shows that the file mc-39281-big-Data.db > blocks 95 expired files from getting dropped, for example the oldest file > mc-22922-big-Data.db > > [BigTableReader(path='.../stat/spa-.../mc-39281-big-Data.db') (minTS = > 1490958782530000, maxTS = 1532707837676719, maxLDT = 1557154990) > blocks 95 expired sstables from getting dropped: > [BigTableReader(path='.../stat/spa-.../mc-36936-big-Data.db') (minTS = > 1500027128958000, maxTS = 1503666765807229, maxLDT = 1535202765) > [BigTableReader(path='.../stat/spa-.../mc-22921-big-Data.db') (minTS = > 1492256093314000, maxTS = 1492775013454001, maxLDT = 1524311013) > [BigTableReader(path='.../stat/spa-.../mc-36947-big-Data.db') (minTS = > 1492255708403000, maxTS = 1501937182477001, maxLDT = 1533473182) > [BigTableReader(path='.../stat/spa-.../mc-32582-big-Data.db') (minTS = > 1493028031639000, maxTS = 1499175057476001, maxLDT = 1530711057) > [BigTableReader(path='.../stat/spa-.../mc-32560-big-Data.db') (minTS = > 1500210297826000, maxTS = 1501416691390001, maxLDT = 1532952691) > [BigTableReader(path='.../stat/spa-.../mc-32528-big-Data.db') (minTS = > 1490958761762000, maxTS = 1504358072394248, maxLDT = 1535894072) > [BigTableReader(path='.../stat/spa-.../mc-32572-big-Data.db') (minTS = > 1500027103795000, maxTS = 1500297137808001, maxLDT = 1531833137) > [BigTableReader(path='.../stat/spa-.../mc-36935-big-Data.db') (minTS = > 1500038582669000, maxTS = 1503839159485824, maxLDT = 1535375159) > [BigTableReader(path='.../stat/spa-.../mc-22922-big-Data.db') (minTS = > 1490958570018000, maxTS = 1492250905633001, maxLDT = 1523786905) > [BigTableReader(path='.../stat/spa-.../mc-33470-big-Data.db') (minTS = > 1499940836241000, maxTS = 1500040376685000, maxLDT = 1531576376) > > Why create the repair such turbulence in new data files and how can we remove > the old data? > > Kind Regards > > Maik Cäsar > > > > DXC Technology Company -- This message is transmitted to you by or on behalf > of DXC Technology Company or one of its affiliates. It is intended > exclusively for the addressee. The substance of this message, along with any > attachments, may contain proprietary, confidential or privileged information > or information that is otherwise legally exempt from disclosure. Any > unauthorized review, use, disclosure or distribution is prohibited. If you > are not the intended recipient of this message, you are not authorized to > read, print, retain, copy or disseminate any part of this message. If you > have received this message in error, please destroy and delete all copies and > notify the sender by return e-mail. Regardless of content, this e-mail shall > not operate to bind DXC Technology Company or any of its affiliates to any > order or other contract unless pursuant to explicit written agreement or > government initiative expressly permitting the use of e-mail for such > purpose. --.
