nodetool settraceprobability

Sets the probability for tracing a request.

Sets the probability for tracing any given request to value.

Probabilistic tracing identifies which queries are responsible for intermittent query performance problems. You can trace some or all statements sent to a cluster. Tracing a request usually requires at least 10 rows to be inserted.

A probability of 1.0 traces everything whereas lesser amounts (for example, 0.10) only sample a certain percentage of statements. Take care on large and active systems, as system-wide tracing will have a performance impact. Unless you are under a very light load, tracing all requests (probability 1.0) will probably overwhelm your system. Start with a small fraction, for example, 0.001 and increase only if necessary.

The trace information is stored in a system_traces keyspace that holds the sessions and events tables that can be easily queried to answer questions, such as what the most time-consuming query has been since a trace was started. Query the parameters map and thread column in the system_traces.sessions and system_traces.events tables for probabilistic tracing information.

Tip: To discover the current trace probability setting, use nodetool gettraceprobability.

Synopsis

nodetool [connection_options] settraceprobability
[--] value
Table 1. Legend
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.
value
  • 0 - disables trace probability. Default.
  • number between 0 and 1 - trace probability to represent a percentage.
  • 1 - enables for all requests.

Examples

Set probability for tracing a request at 60%

nodetool settraceprobability 0.6

Enable tracing for all requests

nodetool settraceprobability 1

Disable request tracing

nodetool settraceprobability 0