Clojurians Log v2

So I’m trying to understand functions, queries and caching a bit better. I have two questions. *Question 1* I’m trying to filter for messages that have content longer than 200 characters:

(d/q '[:where
       [?u :message/content ?content]
       [(> (count ?content) 200)]
       :find (count ?content).]
  @*conn*)
  
=> nil

Doesn’t return anything. Why? I’m assuming you can’t nest functions? Separating out the functions still doesn’t return anything either though:

(d/q '[:where
       [?u :message/content ?content]
       [(count ?content) ?n]
       [(> ?n 200)]
       :find (count ?content).]
       @*conn*)
=> nil       

If I implement my own greater than function this works:

(defn my> [a b]
  (> a b))

(d/q '[:where
       [?u :message/content ?content]
       [(count ?content) ?n]
       [(app.scratch/my2> ?n 200)]
       :find  (count ?content).]
       @*conn*)
=> 5       

Is this because > is special for range queries? *Question 2* If I implement a function for checking spam based on length like below:

(defn spam? [x] (> (count x) 200))

(d/q '[:where
       [?u :message/content ?content]
       [(app.scratch/spam? ?content)]
       :find (count ?content).]
       @*conn*)
=> 5       

I get the expected result. However, if I change the function and run the query again.

(defn spam? [x] (> (count x) 200000))

(d/q '[:where
       [?u :message/content ?content]
       [(app.scratch/spam? ?content)]
       :find (count ?content).]
       @*conn*)
=> 5

The above should return nil (as I have no content that length). So some caching is happening, my question is what are the conditions for this sort of caching (also where’s the best place to look in the source code)? Is there a way to tell datalevin that the function has changed?