What is the meaning of "LocalCollector - Final required fields list" and the list of fields afterward (in search.log)?

[andrewaalin]

What is the significance of the list of fields in "search.log", in the line that contains "INFO LocalCollector - Final required fields list ="?

Let's say there are 100 fields in there and each trace back to a unique EXTRACT line in props; does this mean that all 100 regexes are running against every event?

Why might there be fields in "Final required fields list" that are of a completely unrelated sourcetype relative to the sourcetype specified in the search SPL?

[BobFerguson]

I'm also interested by an answer here, as i noticed the same behaviour

[ehowardl3]

Did you ever find an answer to this? I have the same question.