Hi. A few months ago, I upgraded a single node Cassandra instance from version
3 to 4.1.3. This instance is not very large with about 15 to 20 gigabytes of
data on version 3, but after the update it has went substantially up to over
100gb. I do a compaction once a week and take a snapshot, but with the
increase in data it makes the compaction a much lengthier process. I also did
a sstableupate as part of the upgrade. Any reason for the increased size of
the database on the file system?
I am using the default STCS compaction strategy. My “nodetool cfstats” on a
heavily used table looks like this:
Keyspace : xxxxxxxx
Read Count: 48089
Read Latency: 12.52872569610514 ms
Write Count: 1616682825
Write Latency: 0.0067135265490310386 ms
Pending Flushes: 0
Table: sometable
SSTable count: 13
Old SSTable count: 0
Space used (live): 104005524836
Space used (total): 104005524836
Space used by snapshots (total): 0
Off heap memory used (total): 116836824
SSTable Compression Ratio: 0.566085855123187
Number of partitions (estimate): 14277177
Memtable cell count: 81033
Memtable data size: 13899174
Memtable off heap memory used: 0
Memtable switch count: 13171
Local read count: 48089
Local read latency: NaN ms
Local write count: 1615681213
Local write latency: 0.005 ms
Pending flushes: 0
Percent repaired: 0.0
Bytes repaired: 0.000KiB
Bytes unrepaired: 170.426GiB
Bytes pending repair: 0.000KiB
Bloom filter false positives: 125
Bloom filter false ratio: 0.00494
Bloom filter space used: 24656936
Bloom filter off heap memory used: 24656832
Index summary off heap memory used: 2827608
Compression metadata off heap memory used: 89352384
Compacted partition minimum bytes: 73
Compacted partition maximum bytes: 61214
Compacted partition mean bytes: 11888
Average live cells per slice (last five minutes): NaN
Maximum live cells per slice (last five minutes): 0
Average tombstones per slice (last five minutes): NaN
Maximum tombstones per slice (last five minutes): 0
Dropped Mutations: 0
Droppable tombstone ratio: 0.04983
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