Nodetool toppartitions

New in version 3.1.

toppartitions <keyspace> <table> <duration> - Samples cluster writes and reads and reports the most active partitions in a specified table and time frame.

Note

The command need to be run while there are writes and reads operations.

Parameter

Description

keyspace

The keyspace name

table

The table name

duration

The duration in milliseconds

For example:

nodetool toppartitions nba team_roster 5000

Example output:

WRITES Sampler:
  Cardinality: ~5 (256 capacity)
  Top 10 partitions:
         Partition                Count       +/-
         Russell Westbrook         100         0
         Jermi Grant               25          0
         Victor Oladipo            17          0
         Andre Roberson            1           0
         Steven Adams              1           0

READS Sampler:
  Cardinality: ~5 (256 capacity)
  Top 10 partitions:
         Partition                Count       +/-
         Russell Westbrook         100         0
         Victor Oladipo            17          0
         Jermi Grant               12          0
         Andre Roberson            5           0
         Steven Adams              1           0

In this example we can see that for the Partition with Partition Key “Russell Westbrook” were done 100 writes and 100 read operations during the set duration.

For each of the samplers (WRITES and READS in this specific example), nodetool toppartitions reports:

  • The cardinality of the sampled operations (number of unique operations in the sample set).

  • The number of partitions in a specified table that had the most traffic in a specified time period.

Parameter

Description

Partition

The partition key

Count

The number of operations of the specified type that occurred during the specified time period

+/-

The margin of error for the Count statistic

Write Count

The total number of writes since last boot

Write Latency

The average read latency

To know which node hold the partition key use the nodetool getendpoints command.

For example:

nodetool getendpoints nba team_roster Russell Westbrook

Example output:

10.0.0.72

Nodetool Reference