This is an activity type which allows for the generation of data into to stdout or a file. It reads the standard NoSQLBench YAML format. It can read YAML activity files for any activity type that uses the curly brace token form in statements.

Example activity definitions

Run a stdout activity named 'stdout-test', with definitions from activities/stdout-test.yaml

... driver=stdout workload=stdout-test

Only run statement groups which match a tag regex

... driver=stdout workload=stdout-test tags=group:'ddl.*'

Run the matching 'dml' statements, with 100 cycles, from [1000..1100)

... driver=stdout workload=stdout-test tags=group:'dml.*' cycles=1000..11000 filename=test.csv

This last example shows that the cycle range is [inclusive..exclusive), to allow for stacking test intervals. This is standard across all activity types.

stdout ActivityType Parameters

  • filename - this is the name of the output file (defaults to "stdout", which actually writes to stdout, not the filesystem)
  • newline - whether to automatically add a missing newline to the end of any statements. default: true
  • format - which format to use. If provided, the format will override any statement formats provided by the YAML. valid values are (csv, readout, json, inlinejson, assignments, and diag)
    • When 'format=diag', then the internal construction logic for the binding is logged in detail and NoSQLBench exits. This is useful for detailed diagnostics when you run into trouble, but not generally otherwise. This provides details that you may include in a bug report if you think there is a bindings bug.
  • bindings - This is a simple way to specify a filter for the names of bindings that you want to use. If this is 'doc', then all the document level bindings are used. If it is any other value, it is taken as a pattern (regex) to subselect a set of bindings by name. You can simply use the name of a binding here as well. default: doc


This activity type uses the uniform yaml configuration format. For more details on this format, please refer to the Standard YAML Format

Configuration Parameters

  • newline - If a statement has this param defined, then it determines whether or not to automatically add a missing newline for that statement only. If this is not defined for a statement, then the activity-level parameter takes precedence.

Statement Format

The statement format for this activity type is a simple string. Tokens between curly braces are used to refer to binding names, as in the following example:

 - "It is {minutes} past {hour}."

If you want to suppress the trailing newline that is automatically added, then you must either pass newline=false as an activity param, or specify it in the statement params in your config as in:

 newline: false

Auto-generated statements

If no statement is provided, then the defined binding names are used as-is to create a CSV-style line format. The values are concatenated with comma delimiters, so a set of bindings like this:

 one: Identity()
 two: NumberNameToString()

would create an automatic string template like this:

 - "{one},{two}\n"

The auto-generation behavior is forced when the format parameter is supplied.