Explain case sensitivity of Impala SQL function names

[ianmcook]

This works:

flights %>% 
  group_by(origin) %>% 
  summarise(NDV(dest))

but only if NDV() is uppercase. The README should explain why this is, because function names in Impala SQL are case-insensitive.

[ianmcook]

This was caused by the presence of a window function translation for ndv() without a corresponding aggregate function translation for ndv(). The issue of case sensitivity was a red herring. This is fixed in 6455714.