XML differences

FM/Db2 uses either the ISPF editor or the File Manager editor to display and process changes to data in an XML column. The ISPF editor is used when the size of the XML document is less than or equal to 10 MB. The File Manager and ISPF editors are designed to handle different types of data:
  • The ISPF editor is primarily a text editor, and is well suited to handling XML data.
  • The File Manager editor is primarily a data editor, and is well suited to handling data that has a format that can be described using a template.
An XML document cannot be described using a template.

XML edit differences highlights some important differences between a File Manager/Db2 editor session and an ISPF editor session of an XML document.

Table 1. XML edit differences
Action Object Edit XML Edit
Initiation From the function entry panel. Edit, browse and view editor primary commands. Using the XMLBRWS, XMLEDIT, XMLVIEW editor primary commands from within a File Manager/Db2 editor session of the Db2® object containing the XML column (Originating session).
Saving Changes to rows presented to Db2® one at a time. It is possible that Db2® may reject changes to any row for many reasons. When a SAVE command is issued any changes made to XML columns are presented to Db2®. XML documents are saved when either the XMLEDIT session or the FM/Db2 editor session ends.
Editor used FM/Db2 editor If the size of the XML document is less than or equal to 10 MB, the ISPF editor is used. Otherwise, the File Manager editor is used.
Commit A Db2® commit may be issued at the end of SAVE command, depending on the settings for various editor options. No Db2® commits are issued from within an edit session of an XML document.
Data Display Data is shown initially in either TABL or SNGL format, depending on the settings for the 'Initial display format' editor option. (Displayed on the Editor options (1) panel.) There is only one display format in the ISPF editor. The data is formatted using tag and end-tag pairs prior to display.
Storage As described for "normal" or "large" mode, see Characteristics of editor modes. All of the data for the XML document is written to a temporary data set, and then processed using either the ISPF editor or the File Manager editor. The following constraints might limit the size of the XML document that can be processed:
  • The user's TSO region size.
  • Allocation restrictions on the size of the temporary data set.
  • Disk space constraints.
  • The Db2® LOBVALA parameter (specified in Db2® job DSNTIJUZ). The value of this parameter limits the maximum amount of storage, in KB, that each user is to have for storing LOB values.