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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; |
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.
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
Catching a Hot Partition - Information on how to locate a hot partition
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