Data Assignment Methods for File-Type Parameters

When using File type parameters, a data file contains the parameter values that are assigned to the Vusers during script execution. VuGen lets you specify the way in which you assign data from the source to the parameters. The following methods for assigning data are available:

Assignment method Description

Assigns data to a Vuser sequentially. As a running Vuser accesses the data table, it takes the next available row of data.

If there are not enough values in the data table, VuGen returns to the first value in the table, continuing in a loop until the end of the test.


Assigns a value from a random row in the data table every time a new parameter value is requested.

When you use the Controller to run a Vuser in a Scenario, you can specify a seed number for random sequencing. Each seed value represents one sequence of random values used for test execution. Whenever you use this seed value, the same sequence of values is assigned to the Vusers in the scenario. You enable this option if you discover a problem in the test execution and want to repeat the test using the same sequence of random values.


Allocates a unique block of parameter values to each Vuser in the scenario, and then sequentially assigns values to the parameter for each Vuser from within the Vuser's block of values. Ensure that there is enough data in the table for all Vusers and their iterations. If you have 20 Vusers and you want to perform 5 iterations, your table must contain at least 100 unique values.

Note: If you will be using Network Virtualization Insights to analyze scenario results, LoadRunner will create several additional Vusers, in addition to the Vusers that you defined in the scenario scheduler. Therefore, if the scenario includes a parameter that is assigned values using the unique data assignment method, make sure that the list of parameter values contains several extra values, i.e. several values more than is required by all Vusers to run all their iterations, in order to accommodate the additional Vusers.

If you run out of unique values, VuGen behaves according to the option you select in the When out of values field. For more information, see Parameter Properties Dialog Box.

Note for LoadRunner users: If a script uses Unique file parameterization, running more than one Vuser group with that script in the same scenario may cause unexpected scenario results. For more information about Vuser groups in scenarios, see the Function Reference.