Hi
We have a table that stores metrics but does not have TTL, it is partitioned by
metrics_source, metric_type and clustered by a timestamp.
we are currently using the following TWCS compaction with the settings below.
{'class': 'org.apache.cassandra.db.compaction.TimeWindowCompactionStrategy',
'compaction_window_size': '7', 'compaction_window_unit': 'DAYS',
'max_threshold': '32', 'min_threshold': '4'}
Some relevant info from tablestats and table historgram, currently the
performance is sufficint for our usecase.
SSTable count: 529
Max SSTable size: 15.577GiB
Local read/write ratio: 0.75296SSTables Time Window: 7 DAYS, max duration: 3707
days 4 hours 58 minutes 47 seconds
Local read count: 3823721
Local read latency: 2.129 ms
Local write count: 5078241
Local write latency: 0.011 ms
Percentile Read Latency Write Latency SSTables Partition
Size Cell Count
50% 1597.00 10.00
12.00 17084 1331
75% 1916.00 12.00
20.00 29521 2299
95% 3973.00 29.00
29.00 73457 5722
98% 9887.00 35.00
29.00 126934 9887
99% 14237.00 50.00
35.00 182785 11864
Min 373.00 2.00
0.00 36 0
Max 29521.00 446.00
50.00 8409007 654949
We have recently upgraded to cassandra 5.0.5 and I have been reading about UCS,
since our data does not have TTL we are accumulating sstables with time.
1.
Would you recommend migrating to UCS is it production ready and safe to use?
2.
My scenario has mixed worload, a constant wrote and occasiouanl bursts of
read. Would UCS result in comparable performance or better to TWCS?
3.
Because my data has no TLL, Is there an option in UCS to use a time based
compaction in the lower tiers like TWCS and a SizeBased in higher tier to have
the best of both worlds?
4.
Which UCS settings do you think would be a good starting point to experiemnt.
Best regards,
Isaeed Mohanna
