you are seeing this http://wiki.apache.org/cassandra/FAQ#range_ghosts
Lots of client API's and CQL 3 hide this from you now. Cheers ----------------- Aaron Morton Cassandra Consultant New Zealand @aaronmorton http://www.thelastpickle.com On 17/07/2013, at 1:52 PM, 杨辉强 <huiqiangy...@yunrang.com> wrote: > Thanks, But Michael's answer confuse me more. > > I use list cf; in cassandra-cli. It seems lots of rows have been deleted, but > keys exist. > > After the deletion, why the key still exists? It seems useless. > > RowKey: 3030303031306365633862356437636365303861303433343137656531306435 > ------------------- > RowKey: 3030303031316333616336366531613636373735396363323037396331613230 > ------------------- > RowKey: 3030303031316333616336366531613637303964616364363630663865313433 > ------------------- > RowKey: 3030303031323934613637303239323563633133303238626330646666626335 > ------------------- > RowKey: 3030303031323934613637303239323566303733303638373138366334323436 > ------------------- > RowKey: 3030303031333838333139303930633664643364613331316664363134656639 > ------------------- > RowKey: 3030303031336265343639303630613938376333366230363439316336333230 > ------------------- > RowKey: 3030303031336365653735376465616334633932333363363832653130363733 > ------------------- > RowKey: 3030303031343632343261363966376464656235373266663761633233353065 > > > ----- 原始邮件 ----- > 发件人: "Michael Theroux" <mthero...@yahoo.com> > 收件人: user@cassandra.apache.org > 发送时间: 星期二, 2013年 7 月 16日 下午 10:23:32 > 主题: Re: Deletion use more space. > > The only time information is removed from the filesystem is during > compaction. Compaction can remove tombstones after gc_grace_seconds, which, > could result in reanimation of deleted data if the tombstone was never > properly replicated to other replicas. Repair will make sure tombstones are > consistent amongst replicas. However, tombstones can not be removed if the > data the tombstone is deleting is in another SSTable and has not yet been > removed. > > Hope this helps, > -Mike > > > On Jul 16, 2013, at 10:04 AM, Andrew Bialecki wrote: > >> I don't think setting gc_grace_seconds to an hour is going to do what you'd >> expect. After gc_grace_seconds, if you haven't run a repair within that >> hour, the data you deleted will seem to have been undeleted. >> >> Someone correct me if I'm wrong, but in order to order to completely delete >> data and regain the space it takes up, you need to "delete" it, which >> creates tombstones, and then run a repair on that column family within >> gc_grace_seconds. After that the data is actually gone and the space >> reclaimed. >> >> >> On Tue, Jul 16, 2013 at 6:20 AM, 杨辉强 <huiqiangy...@yunrang.com> wrote: >> Thank you! >> It should be "update column family ScheduleInfoCF with gc_grace = 3600;" >> Faint. >> >> ----- 原始邮件 ----- >> 发件人: "杨辉强" <huiqiangy...@yunrang.com> >> 收件人: user@cassandra.apache.org >> 发送时间: 星期二, 2013年 7 月 16日 下午 6:15:12 >> 主题: Re: Deletion use more space. >> >> Hi, >> I use the follow cmd to update gc_grace_seconds. It reports error! Why? >> >> [default@WebSearch] update column family ScheduleInfoCF with >> gc_grace_seconds = 3600; >> java.lang.IllegalArgumentException: No enum const class >> org.apache.cassandra.cli.CliClient$ColumnFamilyArgument.GC_GRACE_SECONDS >> >> >> ----- 原始邮件 ----- >> 发件人: "Michał Michalski" <mich...@opera.com> >> 收件人: user@cassandra.apache.org >> 发送时间: 星期二, 2013年 7 月 16日 下午 5:51:49 >> 主题: Re: Deletion use more space. >> >> Deletion is not really "removing" data, but it's adding tombstones >> (markers) of deletion. They'll be later merged with existing data during >> compaction and - in the end (see: gc_grace_seconds) - removed, but by >> this time they'll take some space. >> >> http://wiki.apache.org/cassandra/DistributedDeletes >> >> M. >> >> W dniu 16.07.2013 11:46, 杨辉强 pisze: >>> Hi, all: >>> I use cassandra 1.2.4 and I have 4 nodes ring and use byte order >>> partitioner. >>> I had inserted about 200G data in the ring previous days. >>> >>> Today I write a program to scan the ring and then at the same time delete >>> the items that are scanned. >>> To my surprise, the cassandra cost more disk usage. >>> >>> Anybody can tell me why? Thanks. >>> >>
