Rotating a Data Structure for Enhanced Retrieval

How to:

Reference:

If you are using certain network or hierarchical data sources such as IMS, CA-IDMS/DB, or FOCUS, you can rotate the data source, creating an alternate view which changes some of the segment relationships and enables you to access the segments in a different order. By reporting from an alternate view, you can do the following:

It should be noted that retrieval is controlled by the minimum referenced subtree. For more information, see Understanding the Efficiency of the Minimum Referenced Subtree in the Describing a Group of Fields chapter in the Describing Data With WebFOCUS Language manual.

For example, consider the regular and alternate views below:

Since C is the root segment in the alternate view, particular instances of C can be selected faster.


Top of page

x
Syntax: How to Request an Alternate View

To request an alternate view, add the name of a field found in the alternate root segment to the file name in the TABLE command, separated by a period (.):

TABLE FILE filename.fieldname

Top of page

x
Reference: Usage Notes for Restructuring Data


Example: Restructuring Data

Consider the following data structure, in which PROD_CODE is an indexed field:

You could issue the following request to promote the segment containing PROD_CODE to the top of the hierarchy, thereby enabling quicker access to the data in that segment.

TABLE FILE SALES.PROD_CODE
"SALES OF B10 DISTRIBUTED BY AREA"
SUM UNIT_SOLD AND RETAIL_PRICE
BY AREA
WHERE PROD_CODE EQ 'B10'
ON TABLE COLUMN-TOTAL
END

WebFOCUS