I came across such exception these days.
ColumnPartitionedTableStoreExec creates hdfs directories based on partition values. For example is one of the partitions is 'col1=2', a directory named 'col1=2' will be created. If query unit attempt fails, that directory still exist. After that TajoQueryMaster start another query unit attempt to reprocessing the logic in ColumnPartitionedTableStoreExec. This physical executor try to create 'col1=2' again, but before creating, it found the target directory already exist, it will throw an AlreadyExistsStorageException. And eventually, the query fails.