Cassandra Compression Ratio is 0 although LZ4Compressor used - cassandra

Question

I have create a keyspace and table within it for documents store.
The code I used is
CREATE KEYSPACE space WITH replication = {'class':'SimpleStrategy', 'replication_factor' : 3};
USE space;
CREATE TABLE documents (
doc_id text,
path text,
content text,
metadata_id text,
PRIMARY KEY (doc_id)
)
WITH compression = { 'sstable_compression' : 'LZ4Compressor' };
Then I've pushed some data into it and with using a command nodetool cfstats orpd.documents I wanted to check compression ratio.
$ nodetool cfstats space.documents
Keyspace: space
Read Count: 0
Read Latency: NaN ms.
Write Count: 2005
Write Latency: 0.050547132169576056 ms.
Pending Flushes: 0
Table: documents
SSTable count: 0
Space used (live): 0
Space used (total): 0
Space used by snapshots (total): 0
Off heap memory used (total): 0
SSTable Compression Ratio: 0.0
Number of keys (estimate): 978
Memtable cell count: 8020
Memtable data size: 92999622
Memtable off heap memory used: 0
Memtable switch count: 0
Local read count: 0
Local read latency: NaN ms
Local write count: 2005
Local write latency: 0.051 ms
Pending flushes: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 0
Bloom filter off heap memory used: 0
Index summary off heap memory used: 0
Compression metadata off heap memory used: 0
Compacted partition minimum bytes: 0
Compacted partition maximum bytes: 0
Compacted partition mean bytes: 0
Average live cells per slice (last five minutes): 0.0
Maximum live cells per slice (last five minutes): 0.0
Average tombstones per slice (last five minutes): 0.0
Maximum tombstones per slice (last five minutes): 0.0
----------------
However, I got confused because the ratio is 0.0, even though I use a compressor.
I am curious whether more data needs to be put into DB in order to get the measure or I am doing somethig wrong.

Answer 1

Your all data is in memtable
Run the below command to flush your memtable data to sstable
nodetool flush