JMeter: database clob in variable

Question

I have JDBC sample which selects oracle clob inside a variable. However, I need to use the content of this variable in the HTTP request, but the variable expansion doesn't evaluate to clob's content, but it's name instead. If I try to cast the clob to_char in the SQL query, I get an error buffer size is too small. How to correctly convert clob to string in jmeter?

Answer 1

1. For example you have a table with a CLOB field which looks like:

   SQL> select * from sometable;
   
   SOMEDATA
   --------------------------------------------------------------------------------
   hello
   

2. Which is returned to JMeter as something non-readable:

   

3. Declare a "Result Variable Name" with a meaningful reference name, i.e. clob

   

4. Add JSR223 PostProcessor as a child of the JDBC Request sampler and put the following code into "Script" area:

   def data = vars.getObject('clob').get(0).get('SOMEDATA')?.characterStream?.text
   log.info('Value from CLOB field: ' + data)
   

   The above code will extract the value from the CLOB field and print it into jmeter.log file

   

The answer is inspired by the Performance Testing BLOB from a MySQL Database with JMeter article.