IBM AS/400e, Руководство пользователя

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Operating System/400, 5769-SS1
510
AS/400e System Handbook
LOB fields can hold up to 15 MB of data. With the new LOB support, you can look to DB2
Universal Database for AS/400 as a platform for building applications that hold new data
such as very large text, image, and audio data.
• Datalink Data Type
The DATALINK data type extends the types of data that can be stored in database files.
The actual data stored in the column is only a pointer to the object such as an image file,
a voice recording, or a text file. The method used for resolving to the object is to store a
Uniform Resource Locator (URL). This means that a row in a table can be used to contain
information about the object in traditional data types, and the object itself can be
referenced using the DATALINK data type.
Datalinks also allow the referenced object to be “linked” to the database in such a way as
to prevent modification or deletion of the object while it is linked to the database file. This
relationship is maintained by having the database interact with the file system that
contains the object.
• User-Defined Types
User-defined types are derived from existing predefined types such as integer and
character. You can create your own types for strong typing and creating functions for
different types. You can call a function for each row of a result set and return a value
based on the user-defined type.
• User-Defined Functions
SQL lets you define your own functions to use within SQL itself. This saves you time in
reusing common building blocks that you develop yourself. User-defined functions are
necessary building blocks to support the database extenders (extensions to support rich
text and multimedia search and manipulation) currently supported on UDB.
Scalable TCP/IP
Extended scalability and security capabilities are added to three AS/400 Internet and intranet
servers in V4R4.
AS/400 FTP is enhanced with the following features:
• Support for popular graphical FTP clients and Web server development tools. This
enhancement includes support for UNIX format file listings from the AS/400 FTP
server.
• Ability to use directories other than database libraries as the initial working directory
for the AS/400 FTP server.
• Options to create new database files using the system or user default CCSID.
• Ability to transfer files larger than 2 GB in all file systems that support these file sizes.
• Ability to transfer database files containing null field data.