I have just this been told that my first statement is inaccurate: If 'upgradesstable' is run as a routine operation, you might forget about > it and suffer consequences. 'upgradesstable' is not only doing the > compaction.
I should probably have checked upgradesstable closely before making this statement and I definitely will. Yet, I believe the second point still holds though: 'With UDC, you can trigger the compaction of the sstables you want to remove the tombstones from, instead of compacting *all* the sstables for a given table.' C*heers, 2018-04-02 16:39 GMT+01:00 Alain RODRIGUEZ <arodr...@gmail.com>: > Hi, > > it will re-write this table's sstable files to current version, while >> re-writing, will evit droppable tombstones (expired + gc_grace_seconds >> (default 10 days) ), if partition cross different files, they will still >> be kept, but most droppable tombstones gone and size reduced. >> > > Nice tip James, I never thought about doing this, it could have been handy > :). > > Now, these compactions can be automatically done using the proper > tombstone compaction settings in most cases. Generally, tombstone > compaction is enabled, but if tombstone eviction is still an issue, you > might want to give a try enabling 'unchecked_tombstone_compaction' in the > table options. This might claim quite a lot of disk space (depending on the > sstable overlapping levels). > > In case manual action is really needed (even more if it is run > automatically), I would recommend using 'User Defined Compactions' - UDC > (accessible through JMX at least) instead of 'uprade sstable': > > - It will remove the tombstones the same way, but with no side effect if > you are currently upgrading for example. If 'upgradesstable' is run as a > routine operation, you might forget about it and suffer consequences. > 'upgradesstable' is not only doing the compaction. > - With UDC, you can trigger the compaction of the sstables you want to > remove the tombstones from, instead of compacting *all* the sstables for a > given table. > > This last point can prevent harming the cluster with useless compaction, > and even allow the operator to do things like: 'Compact the 10% biggest > sstables, that have an estimated tombstone ratio above 0.5, every day' or > 'compact any sstable having more than 75% of tombstones' as you see fit, > and using information such as the sstables sizes and sstablemetadata to get > the tombstone ratio. > > C*heers, > ----------------------- > Alain Rodriguez - @arodream - al...@thelastpickle.com > France / Spain > > The Last Pickle - Apache Cassandra Consulting > http://www.thelastpickle.com > > 2018-04-02 14:55 GMT+01:00 James Shaw <jxys...@gmail.com>: > >> you may use: nodetool upgradesstables -a keyspace_name table_name >> it will re-write this table's sstable files to current version, while >> re-writing, will evit droppable tombstones (expired + gc_grace_seconds >> (default 10 days) ), if partition cross different files, they will still >> be kept, but most droppable tombstones gone and size reduced. >> It works well for ours. >> >> >> >> On Mon, Apr 2, 2018 at 12:45 AM, Jon Haddad <j...@jonhaddad.com> wrote: >> >>> You’ll find the answers to your questions (and quite a bit more) in this >>> blog post from my coworker: http://thelastpickle >>> .com/blog/2016/07/27/about-deletes-and-tombstones.html >>> >>> Repair doesn’t clean up tombstones, they’re only removed through >>> compaction. I advise taking care with nodetool compact, most of the time >>> it’s not a great idea for a variety of reasons. Check out the above post, >>> if you still have questions, ask away. >>> >>> >>> On Apr 1, 2018, at 9:41 PM, Xiangfei Ni <xiangfei...@cm-dt.com> wrote: >>> >>> Hi All, >>> I want to delete the expired tombstone, someone uses nodetool repair >>> ,but someone uses compact,so I want to know which one is the correct way, >>> I have read the below pages from Datastax,but the page just tells us >>> how to use the command,but doesn’t tell us what it is exactly dose, >>> https://docs.datastax.com/en/cassandra/3.0/cassandra/tools >>> /toolsRepair.html >>> could anybody tell me how to clean the tombstone and give me some >>> materials include the detailed instruction about the nodetool command and >>> options?Web link is also ok. >>> Thanks very much >>> Best Regards, >>> >>> 倪项菲*/ **David Ni* >>> 中移德电网络科技有限公司 >>> >>> Virtue Intelligent Network Ltd, co. >>> Add: 2003,20F No.35 Luojia creative city,Luoyu Road,Wuhan,HuBei >>> Mob: +86 13797007811 <+86%20137%209700%207811>|Tel: + 86 27 5024 2516 >>> <+86%2027%205024%202516> >>> >>> >>> >> >
