Well, so you can connect to some databases, read/write files and make calls to REST API's but it doesn't have a listening API feature that I've managed to see in my quick review. No MQTT either that I could see.
So I think the best approach is probably to use a shared db or file where you use Node-RED to output to the db or file and use KNIME to analyse the data. Or, depending on the use-case, use KNIME to analyse and summarise bulk data and write it to a db or file then use that within Node-RED.
KNIME is clearly designed as a stand-alone tool and doesn't appear to support seamless integration in any way that I can tell.
KNIME is also a typical Java beast of an application with embedded Eclipse and Chromium - it starts up really slowly even on my i7 16GB Windows 10 workstation. So you will need some very significant compute capability to run it on.
There are other ways to handle very large data sets but it depends what type of analysis you want to do along the way.