AS/400 logical files

5 pts.
Tags:
AS/400
Logical Files
Physical File
A PF has 10 LF’s. Normally, when the PF is updated, the data in the LF is immediately reflected. However, there is a scenario wherein when the PF is updated, I (the user) do not want to see the updated data reflected in any of the LF. How do you achieve this objective?

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A logical file does not contain any data. It simply provides services such as indexing, data mapping, etc so that the data stored in the physical file can be access and worked with in a different manner. In general when the physical file data is updated, the logical file immediated reflects this change.

If you want a static view of the underlying data, perhaps for query purposes, the typical approach is to periodically duplicate/copy the physical file and then run queries against logical files built over the static copy.

Logical files do provide some limited capabilities in terms of the underlying data that is seen. If in your update of the physical you set a field to a particular value, then the logical file could have select/omit definitions based on that field that could make the new record not accessible through the logical file. In this case you wouldn’t see the change, but you also wouldn’t see the original data (as it’s no longer there).

Commitment control can be used to restrict access to a change in the physical file until the transaction is committed but again, once the change is committed, the logical file will reflect that change.

What is it you are trying to do? Logical files are intended to provide flexibility over real time data. In your case it sounds like you want a static view of the data, suggesting the need to make a copy of the underlying data.

Bruce Vining

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  • Znason
    I too would like to understand what is this person trying to do(?)
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  • Cwhdpkmh
    I used commitment control like this. I committed the changes once all the details had been written to the detail file - thus the user (or in my case a batch process) would have all the detail records available for the header.
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  • TomLiotta
    It's difficult to understand what the OP is trying to do. But just in case... maybe what is being sought is something like a Materialized Query Table (MQT) with a REFRESH TABLE run at a later time? Updates to the base table wouldn't need to appear immediately in the MQT. Tom
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  • Knowledgeonas400
    how to update pf using normal lf in AS/400
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  • MelanieYarbrough
    Hi Knowledgeonas400, Try searching through the AS/400 tag page to see if your question has already been addressed. If not, please post it in a new thread to ensure that you receive the proper answer. Thanks! Melanie
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