The customer is planning to combine multiple variables into one variable like following example.

[Before]
Variable_A=data_a
Variable_B=data_b
Variable_C=data_c

[After]
Variable_ABC=data_a_data_b_data_c

They want to know if there is any limitation for data size of variable inside DD.

The only limitation would be memory. There is no built-in limit in the runtime. In theroy a collection could be a million entries long or a string contain 2 million characters. In reality it all depends on the memory on the machine and you Java memory settings.

Note use of the '|' character in a string can present issues as that is the "collection" marker the runtime uses when data is submitted from the voice browser to the runtime in the HTTP request.

Thank you!