nodetool tablestats 

Provides statistics about one or more tables.

Provides statistics about one or more tables.

Synopsis 

$ nodetool [ options ] tablestats
[ -H | --human-readable ] 
[ -i  table [, table ] . . . ] [ - - ] 
[ keyspace | table | keyspace.table ] [keyspace | table | keyspace.table ] . . .
Options
Short Long Description
-h --host Hostname or IP address.
-p --port Port number.
-pwf --password-file Password file path.
-pw --password Password.
-u --username Remote JMX agent username.
-F format --format format Output format: json or yaml.
-H --human-readable Display bytes in human readable form: KiB (kibibyte), MiB (mebibyte), GiB (gibibyte), TiB (tebibyte).
-i Ignore the list of tables and display the remaining tables.
keyspace.table List of tables (or keyspace) names.
-- Separates an option from an argument that could be mistaken for a option.

Description 

The nodetool tablestats command provides statistics about one or more tables. It's updated when SSTables change through compaction or flushing. Cassandra uses the metrics-core library to make the output more informative and easier to understand.

nodetool tablestats output for a single table
Name of statistic Example value Brief description Related information
Keyspace libdata Name of the keyspace Keyspace and table
Table libout Name of this table  
SSTable count 3 Number of SSTables containing data for this table How to use the SSTable counts metric
Space used (live) 9592399 Total number of bytes of disk space used by all active SSTables belonging to this table Storing data on disk in SSTables
Space used (total) 9592399 Total number of bytes of disk space used by SSTables belonging to this table, including obsolete SSTables waiting to be GCd Same as above.
Space used by snapshots (total): 0 Total number of bytes of disk space used by snapshot of this table's data About snapshots
Off heap memory used (total)   Total number of bytes of off heap memory used for memtables, Bloom filters, index summaries and compression metadata for this table  
SSTable Compression Ratio 0.367… Ratio of size of compressed SSTable data to its uncompressed size Types of compression options.
Number of keys (estimate) 3 The number of partition keys for this table Not the number of primary keys. This gives you the estimated number of partitions in the table.
Memtable cell count 1022550 Number of cells (storage engine rows x columns) of data in the memtable for this table Cassandra memtable structure in memory
Memtable data size 32028148 Total number of bytes in the memtable for this table Total amount of live data stored in the memtable, excluding any data structure overhead.
Memtable off heap memory used 0 Total number of bytes of off-heap data for this memtable, including column related overhead and partitions overwritten The maximum amount is set in cassandra.yaml by the property memtable_offheap_space_in_mb.
Memtable switch count 3 Number of times a full memtable for this table was swapped for an empty one Increases each time the memtable for a table is flushed to disk. See How memtables are measured article.
Local read count 11207 Number of requests to read tables in the keyspace since startup  
Local read latency 0.048 ms Round trip time in milliseconds to complete the most recent request to read the table Factors that affect read latency
Local write count 17598 Number of local requests to update the table since startup  
Local write latency 0.054 ms Round trip time in milliseconds to complete an update to the table Factors that affect write latency
Pending flushes 0 Estimated number of reads, writes, and cluster operations pending for this table
Important: Monitor this metric to watch for blocked or overloaded memtable flush writers. The nodetool tpstats tool does not report on blocked flushwriters.
Bloom filter false positives 0 Number of false positives reported by this table's Bloom filter Tuning bloom filters
Bloom filter false ratio 0.00000 Fraction of all bloom filter checks resulting in a false positive from the most recent read  
Bloom filter space used, bytes 11688 Size in bytes of the bloom filter data for this table  
Bloom filter off heap memory used 8 The number of bytes of off heap memory used for Bloom filters for this table  
Index summary off heap memory used 41 The number of bytes of off heap memory used for index summaries for this table  
Compression metadata off heap memory used 8 The number of bytes of off heap memory used for compression offset maps for this table  
Compacted partition minimum 1110 Size in bytes of the smallest compacted partition for this table  
Compacted partition maximum bytes 126934 Size in bytes of the largest compacted partition for this table  
Compacted partition mean bytes 2730 The average size of compacted partitions for this table  
Average live cells per slice (last five minutes) 0.0 Average number of cells scanned by single key queries during the last five minutes  
Maximum live cells per slice (last five minutes) 0.0 Maximum number of cells scanned by single key queries during the last five minutes  
Average tombstones per slice (last five minutes) 0.0 Average number of tombstones scanned by single key queries during the last five minutes  
Maximum tombstones per slice (last five minutes) 0.0 Maximum number of tombstones scanned by single key queries during the last five minutes  
Dropped mutations 0.0 The number of mutations (INSERTs, UPDATEs or DELETEs) started on this table but not completed A high number of dropped mutations can indicate an overloaded node.

Examples 

An excerpt of the output of the command reporting on a library data table just flushed to disk.

$ nodetool tablestats keyspace1.standard1
Keyspace: keyspace1
	Read Count: 182849
	Read Latency: 0.11363755339104945 ms.
	Write Count: 435355
	Write Latency: 0.01956930550929701 ms.
	Pending Flushes: 0
		Table: standard1
		SSTable count: 2
		Space used (live): 54131487
		Space used (total): 54131487
		Space used by snapshots (total): 0
		Off heap memory used (total): 309620
		SSTable Compression Ratio: 0.0
		Number of keys (estimate): 376390
		Memtable cell count: 200120
		Memtable data size: 47355786
		Memtable off heap memory used: 0
		Memtable switch count: 2
		Local read count: 182849
		Local read latency: 0.125 ms
		Local write count: 435355
		Local write latency: 0.022 ms
		Pending flushes: 0
		Bloom filter false positives: 11
		Bloom filter false ratio: 0.00009
		Bloom filter space used: 272192
		Bloom filter off heap memory used: 272176
		Index summary off heap memory used: 37444
		Compression metadata off heap memory used: 0
		Compacted partition minimum bytes: 216
		Compacted partition maximum bytes: 258
		Compacted partition mean bytes: 258
		Average live cells per slice (last five minutes): 1.0
		Maximum live cells per slice (last five minutes): 1
		Average tombstones per slice (last five minutes): 1.0
		Maximum tombstones per slice (last five minutes): 1

Using the human-readable option  

Use the human-readable -H option to get output in easier-to-read units. For example:

$ C:\> %CASSANDRA_HOME%nodetool tablestats -H keyspace1.standard1
Keyspace: keyspace1
	Read Count: 182849
	Read Latency: 0.11363755339104945 ms.
	Write Count: 435355
	Write Latency: 0.01956930550929701 ms.
	Pending Flushes: 0
		Table: standard1
		SSTable count: 2
		Space used (live): 51.62 MB
		Space used (total): 51.62 MB
		Space used by snapshots (total): 0 bytes
		Off heap memory used (total): 302.36 KB
		SSTable Compression Ratio: 0.0
		Number of keys (estimate): 376390
		Memtable cell count: 200120
		Memtable data size: 45.16 MB
		Memtable off heap memory used: 0 bytes
		Memtable switch count: 2
		Local read count: 182849
		Local read latency: 0.125 ms
		Local write count: 435355
		Local write latency: 0.022 ms
		Pending flushes: 0
		Bloom filter false positives: 11
		Bloom filter false ratio: 0.00000
		Bloom filter space used: 265.81 KB
		Bloom filter off heap memory used: 265.8 KB
		Index summary off heap memory used: 36.57 KB
		Compression metadata off heap memory used: 0 bytes
		Compacted partition minimum bytes: 216 bytes
		Compacted partition maximum bytes: 258 bytes
		Compacted partition mean bytes: 258 bytes
		Average live cells per slice (last five minutes): 1.0
		Maximum live cells per slice (last five minutes): 1
		Average tombstones per slice (last five minutes): 1.0
		Maximum tombstones per slice (last five minutes): 1
The location of the cassandra.yaml file depends on the type of installation:
Package installations /etc/cassandra/cassandra.yaml
Tarball installations install_location/resources/cassandra/conf/cassandra.yaml