使用impala对大数据量查询distinct的时候出现如下错误
5ab149d_24414dab2c19caca:e54b206c5ab149f_91001337-9d70-4c93-84ce-e7916c1ae804 failed with errno=2 description=Error(2): No such file or directory
Backend 4:Create file /tmp/impala-scratch/24414dab2c19caca:e54b206c5ab149d_24414dab2c19caca:e54b206c5ab149f_91001337-9d70-4c93-84ce-e7916c1ae804 failed with errno=2 description=Error(2): No such file or directory查阅文档发现impala在大数据量处理时会用到磁盘保存中间数据
By default, intermediate files used during large sort, join, aggregation, or analytic function operations are stored in the directory /tmp/impala-scratch.
These files are removed when the operation finishes. (Multiple concurrent queries can perform operations that use the "spill
to disk" technique, without any name conflicts for these temporary files.) You can specify a different location by starting the impalad daemon
with the --scratch_dirs="path_to_directory" configuration
option or the equivalent configuration option in the Cloudera Manager user interface. You can specify a single directory, or a comma-separated list of directories. The scratch directories must be on the local filesystem, not in HDFS. You might specify different
directory paths for different hosts, depending on the capacity and speed of the available storage devices. Impala will not start if it cannot create or read and write files in the "scratch" directory.
If there is less than 1 GB free on the filesystem where that directory resides, Impala still runs, but writes a warning message to its log.
直接到各个impalad节点上创建/tmp/impala-scratch中间目录，并赋予读写权限：
mkdir /tmp/impala-scratch
chmod 777 /tmp/impala-scratch
