Hi,
We are trying to get to exact size of a row in table. All the data is
standard sized. As per dev team, partition size should be 10832 bytes. But
as per tablehistograms partition size is 17084
As per
https://docs.datastax.com/en/archived/cassandra/2.0/cassandra/architecture/architecturePlanningUserData_t.html
expected overhead is 23bytes per row per column.
Question:
- Partition size is compressed or uncompressed?
- compression ratio .40 means 40% reduction in size or 40% after
compression?
-
primary_key_index overhead is stored in sstable or outside
-
Partition size in tablehistograms include overhead size or just actual data?
Here is the information about table.
--- table structure --
CREATE TABLE x.y (
key text,
column1 timestamp,
value blob,
PRIMARY KEY (key, column1)
--- tablehistogram ---
Percentile SSTables Write Latency Read Latency Partition Size
Cell Count
(micros) (micros) (bytes)
50% 1.00 20.50 152.32 17084
372
75% 1.00 20.50 219.34 17084
372
95% 17.00 24.60 785.94 17084
372
98% 17.00 29.52 943.13 17084
372
99% 17.00 35.43 1358.10 17084
372
Min 0.00 4.77 17.09 43
0
Max 17.00 219.34 155469.30 35425
770
--- table stats ---
Read Count: 4122704331
Read Latency: 0.36671174864540634 ms.
Write Count: 9972009145
Write Latency: 0.017737019208880798 ms.
Pending Flushes: 0
Table: raw_data
SSTable count: 16
Space used (live): 1109412902237
Space used (total): 1109412902237
Space used by snapshots (total): 0
Off heap memory used (total): 1160258564
SSTable Compression Ratio: 0.4096557120739874
Number of keys (estimate): 236017001
Memtable cell count: 318143
Memtable data size: 20781581
Memtable off heap memory used: 0
Memtable switch count: 55601
Local read count: 4122704332
Local read latency: 0.226 ms
Local write count: 9972009147
Local write latency: 0.020 ms
Pending flushes: 0
Bloom filter false positives: 163
Bloom filter false ratio: 0.00000
Bloom filter space used: 741096200
Bloom filter off heap memory used: 741096072
Index summary off heap memory used: 90682196
Compression metadata off heap memory used: 328480296
Compacted partition minimum bytes: 43
Compacted partition maximum bytes: 35425
Compacted partition mean bytes: 11619
Average live cells per slice (last five minutes): 27.168724439058366
Maximum live cells per slice (last five minutes): 446
Average tombstones per slice (last five minutes): 1.0
Maximum tombstones per slice (last five minutes): 1
