Identifying File Size Storage Issues
Data stored in small files or partitions may create performance issues. The File size reporting feature helps you identify data that is stored inefficiently in small files or partitions.
A table's data maybe stored in a large number of files, perhaps millions of files. For example, the first time you run an Impala query it loads the metadata for each file, which can cause processing delays. In addition, every time you change a query, refresh the metadata, or add a new file or partition, Impala reloads the metadata. This puts pressure on the NameNode, which stores each file's metadata.
The Workload XM file size reporting enables you to identify tables that have a large number of files or partitions. For example, for queries that run slowly or when an Impala cluster crashes, you can view a table's metadata to determine whether a large number of files or partitions are causing the problem.