create external table if not exists ppp.rrrrr(
trans_id int,
userid int,
xxx string,
yyy string,
zzzzz string,
applydate string,
risk_score int
)
row format delimited fields terminated by ','
stored as textfile
location '/extern_table/aplace';
由于userid字段所定义的字段类型不正确，应该是bigint，结果定义成了int，这样hive中查询出来的userid均为空值，
impala上invalidate metadata ppp.rrrrr
取值时发现userid并不为空，都是有值的。不知是内存残留还是被截取了，感觉更像是内存残留
