Database files allow information to be permanently stored on the system. A database file is subdivided into groups of records called members. There are two types of database files: physical files and logical files.
A physical file is a file that contains data records (similar to disk files on other systems).
A logical file is a database file through which data from one or more physical files can be accessed. The format and organization of this data is different from that of the data in the physical file(s). Each logical file can define a different access path (index) for the data in the physical file(s), and can exclude and reorder the fields defined in the physical file(s).
Distributed files allow a database file to be spread across multiple iSeries servers, while retaining the look and capability of a single database. Performance of large queries can be enhanced by splitting database requests across multiple systems. Distributed files behave in much the same way as DATABASE files. However, since files are distributed across multiple systems, the arrival sequence or relative number cannot be relied upon, and additional time is required for the data link to pass the data between the systems whenever the remote system is accessed.
For more information about accessing distributed files, refer to the ILE COBOL for AS/400 Programmer's Guide.
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