I want to store a table between flow runs so that I can compare the prevous result table (from yesterday) with the current (today) and only keep the difference to do further manipulations.
How would I do this? Wha is the best practice?
You can write data locally once you are done with manipulations. In next workflow iteration (tomorrow if I got it right) read that data and compare with today’s data. Regarding data format you can use KNIME internal format which leads to faster reading/writing data. Table Writer and Table Reader nodes use this format.
Also if both source and destination are database you could utilize DB nodes and functions to perform your task.