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 ] . . .
| 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.
| 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 |