nodetool tablestats

Where is the cassandra.yaml file?

The location of the cassandra.yaml file depends on the type of installation:

Installation Type Location

Package installations + Installer-Services installations

/etc/dse/cassandra/cassandra.yaml

Tarball installations + Installer-No Services installations

<installation_location>/resources/cassandra/conf/cassandra.yaml

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 ] . . .

Tarball and Installer No-Services path:

<installation_location>/resources/cassandra/bin
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 an option.

Description

The nodetool tablestats command provides statistics about one or more tables. It’s updated when SSTables change through compaction or flushing. DataStax Enterprise 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

Table statistics

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 partitions (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

How the database reads and writes data

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

How is data read?

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

How are consistent read and write operations handled?

Pending flushes

0

Estimated number of reads, writes, and cluster operations pending for this table

Monitor this metric to watch for blocked or overloaded memtable flush writers. The nodetool tpstats tool does not report on blocked flushwriters.

Percent repaired

100.0

Percentage of data (uncompressed) marked as repaired across all non-system tables on a node. Tables with a replication factor of 1 are excluded.

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, 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 partitions (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
		Percent repaired: 100.0
		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:

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 partitions (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
		Percent repaired: 100.0
		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

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