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From Jeff Jirsa <jji...@gmail.com>
Subject Re: old big tombstone data file occupy much disk space
Date Sat, 02 Sep 2017 17:34:36 GMT
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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