DATASTAGE——Hashed file stage使用

 原文档：Hashed File stages represent a hashed file, i.e., a file that usesa hashing algorithm for distributing records in one or more groups ondisk. You can use a Hashed File stage to extract or write data, or toact as an intermediate file in a job. The primary role of a Hashed Filestage is as a reference table based on a single key field.
 
        关键设置：
　　Stage tab -> General -> Stage name : stage 名字
                                                   Use direction path : 指定文件路径      

        Input tab -> Columns : 表列定义
　　Output -> General :
       When you extract data from a hashed file, the Hashed File stage has anoutput link. The properties of this link and the column definitions ofthe data are defined on the Outputs page in the Hashed File Stage dialog box.
        The General tab is displayed by default and contains the various fields and options.
        If you intend to read and write from a hashed file at the same time, you must either set up a selection on the Selection tab, or you should select the Record Level Read on the Generaltab. This ensures the file is read in records rather than in groups,and that record locks can operate. Note, however, that this mode ofoperation is much slower and should only be used when there is a clearneed to read and write the same file at the same time.

        Output -> Selection :
        The Selection tab contains optional SELECT clauses for the conditional extraction of data from a file.
        Note: The Selection tab is not available if the hashed file is specified by directory path rather than account name on the Stage page.
        Click on the diagram for more details.