Exclude

Enhanced Definition

In the context of mainframe data processing and utilities, "exclude" refers to the action of filtering out or removing specific records, data elements, or items from a larger set based on defined criteria, preventing them from being processed further or included in an output. It is a fundamental operation for data selection and refinement, commonly used in batch processing.

Key Characteristics

- Data Filtering: Primarily used for selectively removing unwanted data from a data stream, file, or report.
- Conditional Logic: Operates based on specified conditions, such as matching a particular value, pattern, range, or data type within a record.
- Utility-Driven: Commonly implemented using mainframe utilities like DFSORT, SYNCSORT, or ICETOOL through control statements (e.g., OMIT or EXCLUDE in various syntax forms).
- Inverse of INCLUDE: Often used in conjunction with or as an alternative to INCLUDE statements; EXCLUDE specifies what *not* to keep, while INCLUDE specifies what *to* keep.
- Performance Impact: Efficiently implemented by optimized utilities, but complex or poorly defined exclusion logic can impact processing time for very large datasets.

Use Cases

- DFSORT/SYNCSORT Record Selection: Removing records from an input dataset that match specific criteria (e.g., OMIT COND=(1,5,CH,EQ,C'TEST') to exclude records where bytes 1-5 contain 'TEST') before sorting, merging, or copying.
- Report Generation: Filtering out specific transaction types, customer segments, or error records from a file destined for a report, ensuring only relevant data is presented.
- Data Cleansing: Eliminating invalid, duplicate, or obsolete records from a production dataset to maintain data quality and integrity.
- SMF/RMF Data Analysis: When processing System Management Facilities (SMF) or Resource Measurement Facility (RMF) records, utilities might EXCLUDE specific record types or subtypes that are not relevant to a particular performance or accounting analysis.

Related Concepts

EXCLUDE is directly related to INCLUDE, its logical opposite, where one specifies what to keep versus what to discard. It is a core mechanism for DATA FILTERING, which is a broader concept encompassing various methods of selecting subsets of data. SORT/MERGE UTILITIES like DFSORT are the primary tools that implement EXCLUDE functionality via their control statements, often invoked through JCL in batch jobs.

Best Practices:

Precise Criteria: Ensure EXCLUDE conditions are exact and unambiguous to avoid unintentionally removing valid data or failing to remove intended data.
Test Thoroughly: Always test EXCLUDE logic on a representative sample of data before applying it to production datasets to verify correctness and prevent data loss.
Document Logic: Clearly document the