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From Cogumelos Maravilha <cogumelosmaravi...@sapo.pt>
Subject TWCS and autocompaction
Date Tue, 16 Jan 2018 11:07:16 GMT
Hi list,

My settings:

AND compaction = {'class':
'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy',
'compaction_window_size': '4', 'compaction_window_unit': 'HOURS',
'enabled': 'true', 'max_threshold': '64', 'min_threshold': '2',
'tombstone_compaction_interval': '15000', 'tombstone_threshold': '0.2',
'unchecked_tombstone_compaction': 'false'}
    AND compression = {'chunk_length_in_kb': '64', 'class':
'org.apache.cassandra.io.compress.LZ4Compressor'}
    AND crc_check_chance = 0.0
    AND dclocal_read_repair_chance = 0.0
    AND default_time_to_live = 1555200
    AND gc_grace_seconds = 10800
    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';

Running this script:

for f in *Data.db; do
   ls -lrt $f
   output=$(sstablemetadata $f 2>/dev/null)
   max=$(echo "$output" | grep Maximum\ timestamp | cut -d" " -f3 | cut
-c 1-10)
   min=$(echo "$output" | grep Minimum\ timestamp | cut -d" " -f3 | cut
-c 1-10)
   date -d @$max +'%d/%m/%Y %H:%M:%S'
   date -d @$min +'%d/%m/%Y %H:%M:%S'
done

on sstables I'm getting values like these:

-rw-r--r-- 1 cassandra cassandra 12137573577 Jan 14 20:08
mc-22750-big-Data.db
14/01/2018 19:57:41
31/12/2017 19:06:48

-rw-r--r-- 1 cassandra cassandra 4669422106 Jan 14 06:55
mc-22322-big-Data.db
12/01/2018 07:59:57
28/12/2017 19:08:42

My goal is using TWCS for sstables expired fast because lots of new data
is coming in. What is the best approach to archive that? Should I
disable auto compaction?
Thanks in advance.


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