Easytrieve File Conversion Projects

Conversion Project Lifecycle

Dual Layout Library Section

Define OLD-RECORD and NEW-RECORD field lists in Library with explicit positions and types. Conversion clarity demands separate FILE statements for SOURCE and TARGET even when both are sequential—different LRECL values. Map field by field in CONVERT-RECORD PROC; document unmapped legacy filler as spaces in new layout. When old field splits into two new fields—combined name becomes FIRST and LAST—use PARSE or substring MOVE per release grammar.

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FILE SOURCE-FILE SEQUENTIAL 200
  OLD-ACCT     1   9  N
  OLD-NAME    10  30  A
  OLD-BAL     40   7  P 2
END-FILE
 
FILE TARGET-FILE SEQUENTIAL 350
  NEW-ACCT     1  16  A
  NEW-NAME    17  46  A
  NEW-BAL     47  15  N 2
END-FILE

CONVERT-RECORD PROC

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JOB INPUT SOURCE-FILE
  ADD 1 TO READ-COUNT
  PERFORM CONVERT-RECORD
  IF VAL-STATUS NE ZERO
     PERFORM WRITE-ERROR
  ELSE
     WRITE TARGET-FILE
     ADD 1 TO WRITE-COUNT
  END-IF
END-JOB
 
CONVERT-RECORD. PROC
  MOVE OLD-ACCT TO NEW-ACCT
  MOVE OLD-NAME TO NEW-NAME
  MOVE OLD-BAL  TO NEW-BAL
  PERFORM VALIDATE-CONVERTED
END-PROC

VALIDATE-CONVERTED checks mandatory new fields—non-blank account, balance within range—before WRITE. Leading-zero account expansion might PERFORM PAD-ACCOUNT moving OLD-ACCT into sixteen-character NEW-ACCT with MASK.

Date Format Migration

Legacy files store dates as YYMMDD packed, Julian YYDDD, or MMDDYY display. New systems expect CCYYMMDD display or ISO strings. Conversion PROC holds intermediate WORK-DATE fields; use date functions documented in date functions tutorial—never assume implicit conversion. Document century expansion rule for YY years—70–99 map to 1970–1999 versus 2070–2099 per shop policy. Wrong century breaks age calculations downstream for decades.

Code Table Translation

Legacy status codes A/B/C map to new codes 01/02/03. Load CODE-XREF TABLE in INIT-JOB; SEARCH in CONVERT-RECORD sets NEW-STATUS from OLD-STATUS. Unmapped codes set VAL-STATUS and ERROR-FILE row—do not default silently to zero unless spec allows. TABLE-driven conversion survives code set changes without recompiling IF ladders when operations maintain TABLE file.

Header and Trailer Handling

Header records

IF RECORD-TYPE = 'H' on first row: WRITE new-format header with conversion run date and source file identifier; skip or transform per spec. Some conversions strip old headers and write new standard header only once in INIT-JOB.

Trailer records

Accumulate WRITE-COUNT and amount sums in JOB; at EOF after detail loop, PERFORM WRITE-TRAILER moving counts to new trailer layout. Downstream validation jobs compare trailer to detail—missing trailer is cutover blocker.

Parallel Run Discipline

1. Legacy job continues producing OLD-FILE.
2. Easytrieve conversion produces NEW-FILE nightly.
3. Comparison job or manual tool verifies READ-COUNT equals WRITE-COUNT plus rejects.
4. Hash totals on key amounts match within tolerance.
5. Sample record diff on fifty random keys—field-by-field.
6. Sign-off document before switching downstream consumers to NEW-FILE only.

JCL Considerations

Performance on Large Conversions

Billion-record conversions run overnight—minimize DISPLAY per record, use adequate BLKSIZE, consider splitting by key range with multiple JCL steps if restart required. Pure byte copy without transform may stay with IEBGENER; Easytrieve earns its cost when every record needs logic. Profile elapsed time on ten-percent sample before full production volume.

Common Conversion Mistakes

• Wrong output LRECL—truncation or padding garbage.
• Ignoring packed decimal scale on MOVE to display numeric.
• No ERROR-FILE—bad records poison TARGET.
• Cutover without parallel hash comparison.
• Assuming sort order preserved when adding header/trailer—document order requirements.

Explain It Like I'm Five

Your toy box has labels in one color sticky notes; the new box wants different color notes with more words. File conversion is moving each toy and rewriting the label to fit the new box rules. Broken toys go in a reject pile instead of the new box. Grown-ups count toys in both boxes to make sure none got lost before throwing away the old box.

Exercises

1. Draw old and new field maps for a ten-field customer record with expanded account number.
2. Write CONVERT-RECORD with TABLE status translation and VAL-STATUS check.
3. List five parallel run checks before cutover sign-off.
4. Describe header and trailer handling for a file with control records.
5. When would you use utility copy instead of Easytrieve conversion? Write three criteria.