nodetool tablestats
Provides statistics about tables.
Provides statistics about tables.
Synopsis
nodetool <options> tablestats -i -- (<keyspace>.<table> ... ) -H
--separates an option from an argument that could be mistaken for a option.-iexcludes the following list of tables from the tool's report. tablestat reports on all other tables in all other keyspaces.tablespecifies the table that the tool reports on. Usekeyspaceand a dot to specify the table's keyspace. to get stats on two or more tables, add more names (with optional keyspace names) separated by spaces.If you run the command with no table names, nodetool tablestats reports on all tables in all keyspaces.
-Hconverts bytes to a human readable form: kilobytes (KB), megabytes (MB), gigabytes (GB), or terabytes (TB).
Description
The nodetool tablestats command provides statistics about one or more tables. Cssandra uses the metrics-core library to make the output more informative and easier to understand.
This table lists the components of the 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. |
| Space used by snapshots (total), bytes: | 0 | Same occupied by backup data | |
| SSTable compression ratio | 0.367. . . | Fraction of data-representation size resulting from compression | Types of compression option) |
| 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 | |
| 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
This example shows an excerpt of the output of the command after flushing a table of library data to disk.
nodetool tablestats libdata.libout
Keyspace: libdata
Read Count: 11207
Read Latency: 0.047931114482020164 ms.
Write Count: 17598
Write Latency: 0.053502954881236506 ms.
Pending Flushes: 0
Table: libout
SSTable count: 3
Space used (live): 9088955
Space used (total): 9088955
Space used by snapshots (total): 0
Off heap memory used (total): 57
SSTable Compression Ratio: 0.8823529411764706
Number of keys (estimate): 3
Memtable cell count: 0
Memtable data size: 0
Memtable off heap memory used: 0
Memtable switch count: 3
Local read count: 11207
Local read latency: 0.048 ms
Local write count: 17598
Local write latency: 0.054 ms
Pending flushes: 0
Bloom filter false positives: 0
Bloom filter false ratio: 0.00000
Bloom filter space used: 11688
Bloom filter off heap memory used: 8
Index summary off heap memory used: 41
Compression metadata off heap memory used: 8
Compacted partition minimum bytes: 1110
Compacted partition maximum bytes: 126934
Compacted partition mean bytes: 2730
Average live cells per slice (last five minutes): 0.0
Maximum live cells per slice (last five minutes): 0
Average tombstones per slice (last five minutes): 0.0
Maximum tombstones per slice (last five minutes): 0
Dropped Mutations: 0
Using the human-readable option
Use the human-readable -H option to get output in easier-to-read units.
For example:
nodetool tablestats cycling.calendar -H Keyspace: cycling Read Count: 0 Read Latency: NaN ms. Write Count: 20050 Write Latency: 0.08548014962593516 ms. Pending Flushes: 0 Table: nhanes SSTable count: 1 Space used (live): 13.75 MB Space used (total): 13.75 MB Space used by snapshots (total): 0 bytes SSTable Compression Ratio: 0.3064650643762481 Memtable cell count: 0 Memtable data size: 0 bytes Memtable switch count: 1 Local read count: 0 Local read latency: NaN ms Local write count: 20050 Local write latency: 0.085 ms Pending flushes: 0 Bloom filter false positives: 0 Bloom filter false ratio: 0.00000 Bloom filter space used: 23.73 KB Compacted partition minimum bytes: 1.87 KB Compacted partition maximum bytes: 2.69 KB Compacted partition mean bytes: 2.26 KB 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 ----------------
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 |