[impala-user] impala sql failed with errno=2 description=Error(2): No such file or directory

cdh5.2.0 ,impala 2.0.

Every hour I will pull data from hive to impala(parquet file).Sometimes,can not excute sql like below，and restart the impala cluster could solve the problem,why?

select id,sub1,(ifnull(sum(click),0)) as clicks > from new_td_impala_test
where (part1>='2014-11-06' and part1<='2014-11-06') and (unix_timestamp(substr(time_stamp,1,19)) >= unix_timestamp('2014-10-31 16:00:00') and unix_timestamp(substr(time_stamp,1,19)) < unix_timestamp('2014-11-07 16:00:00')) group by id,sub1 limit 4 ;
Query: select id,sub1,(ifnull(sum(click),0)) as clicks
from new_td_impala_test
where (part1>='2014-11-06' and part1<='2014-11-06') and (unix_timestamp(substr(time_stamp,1,19)) >= unix_timestamp('2014-10-31 16:00:00') and unix_timestamp(substr(time_stamp,1,19)) < unix_timestamp('2014-11-07 16:00:00')) group by id,sub1 limit 4
WARNINGS: Create file /tmp/impala-scratch/7241111ac15574e0:abef55f7a589b3a5_7241111ac15574e0:abef55f7a589b3a7_dc8fc8e3-f98c-41e8-a86a-d9c8f7840cdb failed with errno=2 description=Error(2): No such file or directory

Backend 1:Create file /tmp/impala-scratch/7241111ac15574e0:abef55f7a589b3a5_7241111ac15574e0:abef55f7a589b3a7_dc8fc8e3-f98c-41e8-a86a-d9c8f7840cdb failed with errno=2 description=Error(2): No such file or directory

I had the same error.
I guess this is a bug. But in my case table has a huge number of partitions.
After I reduced partitions the error disappeared.