May 19, 2014

How to correlate dynamic boundaries in LoadRunner?

Every performance testers must know about how to correlate, no matter which tool they are using. Correlation is nothing but capturing the dynamic data (response) from the server and send the captured response to the subsequent requests.

To capture the dynamic data from the server, in LoadRunner we use web_reg_save_param function. In web_reg_save_param function, we use following parameters: Left boundary, Right boundary, Ord, SaveLen etc.

E.g. consider below is the dynamic data from the server which has the LB and RB as <span class=”login-bold”> and </span> respectively.

 [stextbox id=”grey”]<span class=”login-bold”>@oiewhvsj@$39945ksjklsg</span>[/stextbox]

In above case, we can easily capture the dynamic data and pass it to subsequent requests. But what if the left and right boundaries changes dynamically? How to handle dynamic boundaries? In this article, we are going to see about how to correlate dynamic boundaries in LoadRunner.

E.g. consider the below response from the server which has the dynamic boundaries.

 [stextbox id=”grey”]





The left and right boundaries are OrderID1234, OrderID3456, OrderID8798 and 1234, 3456, and 8798 respectively. The dynamic data is dynamicresponsedata

To capture the dynamicresponsedata by using left and right boundaries (of course that is also dynamic in nature), use below syntax:

 [stextbox id=”grey”]

web_reg_save_param(“Correlation_1”, “LB/DIG= OrderID####\=”, “RB=####”, LAST);


you need to enter DIG to interpret # (hash) tag where you expect digit. You can use IC flag i.e. ignore case flag in your function as shown below. Apart from IC, DIG, you can also use ALNUM (alpha numeric), to specify binary data, use /BIN

 [stextbox id=”grey”]

web_reg_save_param(“Correlation_2”, “LB/IC/DIG= OrderID####\=”, “RB/IC=####”, LAST);


If the left and right boundaries has dynamic string e.g. four letter user name, you use below syntax.


[stextbox id=”grey”]

web_reg_save_param(“Correlation_3”, “LB/IC/DIG= OrderID^^^^\=”, “RB/IC=^^^^”, LAST);


About NaveenKumar Namachivayam

Hi there! is a passionate and experienced Performance Test Analyst based in Chicago, USA with skill sets in Manual Testing, Test Automation, Performance Testing, and Test Estimation. He loves to learn and experiment new trends and models in Software Testing. Please stop by at his personal blogs: Excel Blog, DealsBrook,, and Affiliate Insights blog and Software Testing Memes.

11 Comments on “How to correlate dynamic boundaries in LoadRunner?

August 30, 2015 at 4:18 pm

what if the left boudary is not constant
ex. abcd123/hyderabad>” here left boudary is= abcd123/ Rb=>”
abcde12345=chennai>” here lb=abcde12345= Nd rb=>”
bcedf123456*mumbai>” here lb=bcedf123456* and rb=>”
could u please tell me how to correlate now

NaveenKumar N
November 9, 2015 at 12:53 am

In this case, you can use regular expressions in the web_reg_save_param_ex(); function.

October 6, 2015 at 12:01 pm

Hi Naveen,
How to do correlation, if there is no left boundary.. Please let me know.


NaveenKumar N
October 15, 2015 at 5:58 am

You can use web_reg_find(); function.

May 19, 2016 at 6:55 pm

Thanks Naveen.. What would I do , if boundaries like,

Please advice which funtion I should use here, and explain how it works…


May 19, 2016 at 7:11 pm

Hi Naveen,

Have one more doubt here in Jmeter,
i=charts_0/chart_0_2.png&g=93a696c6864046e8bc5dcc36881c80ad is a response from the server.

Where “g=” is left boundary and not able to mark anything here as my right boundary..

Can u assist, how to work without right/left boundary in Jmeter

December 13, 2016 at 11:20 am

Hi Karthikkumar R,

You can use the below Regular expression to get the g value alone.

g=(\S+), it will retrieve the value without giving the right boundary. Please
Note : \s is used to for escape from space + is used for get the required value

May 12, 2016 at 8:08 pm

Hi Naveen,

What if left and right boundaries have special characters and are dynamic values?

NaveenKumar N
May 15, 2016 at 5:13 am

You need to use Regular expressions 🙂

February 6, 2017 at 12:31 pm

Hi Naveen,

How do i correlate boundaries are dynamic using web_reg_save_param_regex function?

May 22, 2017 at 2:33 pm


I want to correlate the field(RollNo=123456&amp)

where my LB=RollNo= and what would be my right boundary.

If I give my RB as RB=&amp, LR is throwing error during run time as No match found for the requested parameter.

Thanks in Advance


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