Result spooling has been relatively stable since it was introduced, and it has several benefits described in
IMPALA-8656. It would be good to enable it by default.
I looked into doing this a while ago, and there are a bunch of tests that rely on the "fetch one row batch at a time" behavior. Those tests fail when result spooling is enabled.
The remaining linked tasks in
IMPALA-8656 should be completed as well before enabling result spooling by default.