RJDBC Parallel query in R

Question

I have a code header that looks something like this in SQL Developer:

    ALTER SESSION ENABLE PARALLEL QUERY
    SELECT /*+PARALLEL(dfam 32)*/
    distinct dfam.a,dfam.b from d_f_a_market dfam;

I am trying to use parallel query in R using RJDBC. I have a code that looks like this:

queryResults <- dbGetQuery(conn, "
SELECT /* +PARALLEL(dfam 32)*/
distinct dfam.a,dfam.b from d_f_a_market dfam;")

But I can't see any time improvement on using the hint. The query takes the same amount of time without sql hint. Any thoughts?