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From Shalom Sagges <shal...@liveperson.com>
Subject Re: old big tombstone data file occupy much disk space
Date Sun, 03 Sep 2017 11:55:50 GMT
Try this blog by The Last Pickle:

http://thelastpickle.com/blog/2016/10/18/user-defined-compaction.html






Shalom Sagges
DBA
<http://www.linkedin.com/company/164748> <http://twitter.com/liveperson>
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On Sat, Sep 2, 2017 at 8:34 PM, Jeff Jirsa <jjirsa@gmail.com> wrote:

> If you're on 3.0 (3.0.6 or 3.0.8 or newer I don't remember which), TWCS
> was designed for ttl-only time series use cases
>
> Alternatively, if you have IO to spare, you may find LCS works as well
> (it'll cause quite a bit more compaction, but a much higher chance to
> compact away tombstones)
>
> There are also tombstone focused sub properties to more aggressively
> compact sstables that have a lot of tombstones - check the docs for
> "unchecked tombstone compaction" and "tombstone threshold" - enabling those
> will enable more aggressive automatic single-sstable compactions
>
> --
> Jeff Jirsa
>
>
> On Sep 2, 2017, at 7:10 AM, qf zhou <zhouqf2013@gmail.com> wrote:
>
>
> Yes, your are right. I am using STCS compaction strategy with some kind of
> timeseries model. Too much disk space has been occupied.
>
> What should I  do to stop  the  disk full ?
>
>  I only want to keep 100 days data most recently,  so I set default_time_to_live
> = 8640000(100 days ).
>
> I know I need to do something to stop the disk space cost, but I really
> don’t know how to do it.
>
>
> Here is the strategy of the big data table :
>
>     AND compaction = {'class': 'org.apache.cassandra.db.compaction.SizeTieredCompactionStrategy',
> 'max_threshold': '32', 'min_threshold': '12', 'tombstone_threshold': '0.1',
> 'unchecked_tombstone_compaction': 'true'}
>     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 = 0.1
>     AND default_time_to_live = 8640000
>     AND gc_grace_seconds = 432000
>
>
>
> 在 2017年9月2日,下午7:34,Nicolas Guyomar <nicolas.guyomar@gmail.com>
写道:
>
> your are using STCS compaction strategy with some kind of timeseries
> model, and you are going to end up with yor disk full!
>
>
>

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