Caution

You're viewing documentation for an unstable version of ScyllaDB Open Source. Switch to the latest stable version.

ScyllaDB Docs ScyllaDB Open Source ScyllaDB for Administrators Admin Tools Nodetool Nodetool toppartitions

Nodetool toppartitions¶

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

toppartitions [<–ks-filters ks>] [<–cf-filters tables>] [<-d duration>] [<-s|–capacity capacity>] [<-a|–samplers samplers>]

Note

The command needs 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

Additional parameters from ScyllaDB 4.6

Parameter	Description
ks-filters	List of keyspaces
cf-filters	List of Tables (Column Families)
duration	The duration in milliseconds
capacity	The capacity of the sampler; higher values increase accuracy at the cost of memory (default 256 keys).
samplers	The samplers to use; `WRITES`, `READS`, or both (default).

For example:

nodetool toppartitions nba team_roster 5000

For Example (Starting from ScyllaDB 4.6):

listing the top partitions from all tables in all keyspaces nodetool toppartitions
listing the top partitions for the last 1000 ms nodetool toppartitions -d 1000
listing the top partitions from a list of tables nodetool toppartitions --cf-filters ks:t,system:status
listing the top partitions from all tables from a list of keyspaces nodetool toppartitions --ks-filters ks,system
combining lists of keyspaces and tables nodetool toppartitions --ks-filters ks --cf-filters system:local

Note

In ScyllaDB 4.6, duration parameter requires a -d prefix

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”, 100 writes and 100 read operations were done 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.

Output¶

Parameter	Description
Partition	The Partition Key, prefixed by the Keyspace and table (ks:cf) for ScyllaDB 4.6 and later
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.

If the margin of error column (+/-) approaches the Count column, the measurement is inaccurate. You can increase accuracy by specifying the --capacity option.

For example:

nodetool getendpoints nba team_roster Russell Westbrook

Example output:

10.0.0.72

Additional Information¶

Catching a Hot Partition - Information on how to locate a hot partition
Nodetool Reference

Was this page helpful?