Starting Journaling with STRJRNPF

Learning Objective

By the end of this lesson, you will be able to explain the basic steps involved in starting journaling for a physical file.

Simple Explanation

Turning on journaling for a table involves a few pieces already introduced earlier in this batch, brought together: a journal receiver to hold entries, a journal to point at that receiver, and finally STRJRNPF to actually start journaling the table itself.

CRTJRNRCV JRNRCV(MYLIB/CUSTJRN0001)
CRTJRN JRN(MYLIB/CUSTJRN) JRNRCV(MYLIB/CUSTJRN0001)
STRJRNPF FILE(MYLIB/CUSTMAST) JRN(MYLIB/CUSTJRN)

Once this runs successfully, every insert, update, and delete against CUSTMAST also produces a journal entry in CUSTJRN0001, exactly as described in the What is Journaling lesson earlier in this batch.

Why It Matters

Seeing the actual sequence, create a receiver, create a journal pointing at it, then start journaling the table, makes the relationship between these objects concrete rather than abstract. This is also the point at which a table transitions from having no change history at all to having every subsequent change recorded, which is a meaningful step that should be taken deliberately, not accidentally.

Practical Example

Imagine CUSTMAST has been in use for some time without journaling. Running the three commands above starts recording every change from that point forward, but it does not retroactively create entries for changes that already happened before journaling started. Understanding this distinction, journaling only covers changes made after it starts, not a table's entire history, matters for setting expectations correctly.

This is a simplified, illustrative example rather than a specific real migration, but it reflects exactly how journaling gets started in practice.

Common Confusions

"Does STRJRNPF also create the journal and receiver automatically?" No. The journal and its receiver need to already exist, created with CRTJRNRCV and CRTJRN as shown above, before STRJRNPF can point a table at that journal.

"Does starting journaling capture changes that happened before STRJRNPF ran?" No. Journaling only records changes made after it starts. Changes made to the table before that point are not retroactively captured.

"Can more than one table be journaled to the same journal?" Yes. A single journal, and its receivers, can hold entries from multiple journaled tables at once; a shop is not limited to one journal per table.

Quick Recap

• Starting journaling for a table involves creating a receiver, creating a journal pointing at that receiver, and then running STRJRNPF to journal the table itself.
• Journaling only records changes made after it starts, not a table's history before that point.
• A single journal and its receivers can hold entries from multiple journaled tables.
• This sequence brings together the journal, receiver, and journaled table concepts already introduced earlier in this batch.

Try Asking the AI Tutor

Use the AI Tutor to ask follow-up questions about this lesson. For example, try asking:

• "Why does it matter that journaling only captures changes going forward, not a table's past history?"
• "What would happen if I ran STRJRNPF against a table but pointed it at a journal that did not actually exist yet?"