nodetool toppartitions
Samples database reads and writes and reports the most active partitions.
Samples the activity in a table during the specified duration and reports the most active partitions.
Synopsis
nodetool [connection_options] toppartitions [-a samplers] [-k num_partitions] [-s size] [--] keyspace_name table_name duration
Syntax conventions | Description |
---|---|
UPPERCASE | Literal keyword. |
Lowercase | Not literal. |
Italics |
Variable value. Replace with a valid option or user-defined value. |
[ ] |
Optional. Square brackets ( [ ] ) surround optional command
arguments. Do not type the square brackets. |
( ) |
Group. Parentheses ( ( ) ) identify a group to choose from. Do
not type the parentheses. |
| |
Or. A vertical bar ( | ) separates alternative elements. Type
any one of the elements. Do not type the vertical bar. |
... |
Repeatable. An ellipsis ( ... ) indicates that you can repeat
the syntax element as often as required. |
'Literal string' |
Single quotation ( ' ) marks must surround literal strings in
CQL statements. Use single quotation marks to preserve upper case. |
{ key:value } |
Map collection. Braces ( { } ) enclose map collections or key
value pairs. A colon separates the key and the value. |
<datatype1,datatype2> |
Set, list, map, or tuple. Angle brackets ( < > ) enclose
data types in a set, list, map, or tuple. Separate the data types with a comma.
|
cql_statement; |
End CQL statement. A semicolon ( ; ) terminates all CQL
statements. |
[ -- ] |
Separate the command line options from the command arguments with two hyphens (
-- ). This syntax is useful when arguments might be mistaken for
command line options. |
' <schema> ... </schema>
' |
Search CQL only: Single quotation marks ( ' ) surround an entire
XML schema declaration. |
@xml_entity='xml_entity_type' |
Search CQL only: Identify the entity and literal value to overwrite the XML element in the schema and solrconfig files. |
Definition
The short form and long form parameters are comma-separated.
Connection options
- -h, --host hostname
- The hostname or IP address of a remote node or nodes. When omitted, the default is the local machine.
- -p, --port jmx_port
- The JMX port number.
- -pw, --password jmxpassword
- The JMX password for authenticating with secure JMX. If a password is not provided, you are prompted to enter one.
- -pwf, --password-file jmx_password_filepath
- The filepath to the file that stores JMX authentication credentials.
- -u, --username jmx_username
- The user name for authenticating with secure JMX.
Command arguments
--
- Separates an option from an argument that could be mistaken for a option.
- -a samplers, samplers2
- Comma-separated list of samplers. Default is all.
- duration
- Duration in milliseconds.
- -k num_partitions
- Number of top partitions. Default is 10.
- keyspace_name
- The keyspace name.
- -s size
- Capacity of stream summary. A value closer to actual cardinality of partitions yields more accurate results. Default is 256.
- table_name
- The table name.
Examples
Sample the most active partitions for the table test.users
for 1,000
milliseconds.
nodetool toppartitions test users 1000
The output of nodetool toppartitions is similar to the following:
WRITES Sampler:
Cardinality: ~2 (256 capacity)
Top 4 partitions:
Partition Count +/-
4b504d39354f37353131 15 14
3738313134394d353530 15 14
4f363735324e324e4d30 15 14
303535324e4b4d504c30 15 14
READS Sampler:
Cardinality: ~3 (256 capacity)
Top 4 partitions:
Partition Count +/-
4d4e30314f374e313730 42 41
4f363735324e324e4d30 42 41
303535324e4b4d504c30 42 41
4e355030324e344d3030 41 40
WRITES
and READS
in the
example), toppartitions reports:- The cardinality of the sampled operations (that is, the number of unique operations in the sample set)
The
n
partitions in the specified table that had the most traffic in the specified time period (wheren
is the value of the-k
argument, or ten if-k
is not explicitly set in the command).For each Partition, toppartitions reports:
- 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 statisticNote: To keep the toppartitions reporting from slowing performance, the database does not keep an exact count of operations, but uses sampling techniques to create an approximate number. (This example reports on a sample cluster; a production system might generate millions of reads or writes in a few seconds.) The
+/-
figure allows you to judge the accuracy of the toppartitions reporting.