Major Description
Cache can't work normally if there are case letters in SQL,
for example:
sql("CREATE TABLE IF NOT EXISTS src (key INT, value STRING) USING hive")
sql("select key, sum(case when Key > 0 then 1 else 0 end) as positiveNum " +
"from src group by key").cache().createOrReplaceTempView("src_cache")
sql(
s"""select a.key
from
(select key from src_cache where positiveNum = 1)a
left join
(select key from src_cache )b
on a.key=b.key
""").explain
The subquery "select key from src_cache where positiveNum = 1" on the left of join can use the cache data, but the subquery "select key from src_cache" on the right of join cannot use the cache data.
