HP 3000 Manual page 10

Characteristics of XSORT:
In extending and enhancing your sort capabilities, XSORT:
• Uses from one to nine input files.
• Employs multiple logical criteria to select records from MPE (disk and non-disk) and KSAM files, so you
can process a subset of your input records.
• Builds a different sort key for each type of record using input record fields and forced control fields. This
facilitates the input of files with different data structures.
• Reformats each type of record upon output to give you a choice of record layouts.
• Can perform a count-only pass on the input files. This permits you to conduct a preliminary search of
your records or provide statistics on selected subsets of records.
How XSORT Works
XSORT follows a logical sequence in performing a sort. This sequence is described below:
1 XSORT reads a record from the input file.
2 XSORT checks your specifications to make sure the record is one you want to sort. You may not
wish to sort all the records in the file you have specified.
3 XSORT builds a work record containing sort control fields and data fields. It also formats the data
portion according to your specifications. Work record formatting is important because it controls
the format of your output.
4 XSORT submits the work records to the SORT subsystem for sorting.
5 XSORT retrieves records from SORT after sorting is complete.
6 XSORT writes records into the output file, retaining or dropping control fields, according to your
specifications
NOTE
Control fields are input fields whose characteristics are used as a basis for the com-
parisons required by the sort. Control fields are discussed in detail in the section on
Field Descriptions. (See chapter 6.)
-------------------------------------------------------
|
| Control field
| A
|
-------------------------------------------------------
1
Suppose that you wanted to rearrange the input file above because a proposed sort job requires the
following changes:
1 Change the contents of positions 30 through 36 placed in positions 1 through 7 of the work record.
2 Change the contents of positions 1 through 10 of the input file placed in positions 8 through 17 of
the work file.
3 Change the contents of positions 11 through 29 of the input record placed in positions 18 through
1- 12
|
| Data
|
|
10 11 29 30
|
| Control field
| B
|
36
|
|
|
|