RE: Level Check Question (jt)

[qsrvbas@xxxxxxxxxxxx (Tom Liotta)]

midrange-l-request@xxxxxxxxxxxx wrote:

>   9. RE: Level Check Question (jt) (jt)
>
>| Isn't this a practical side-effect of DDS LFs anyway? As long as
>| (1) the LF _explicitly_ lists fields and (2) programs use the LF
>| to access the data, there should be no problems if new fields are
>| added to the PF nor if the fields are rearranged in the PF. (It
>| doesn't matter if fields are added at the end, in the middle or wherever.)
>
>That's correct, and was the standard in the first 38 shop I worked in
>(Liebert in '82).  There are other benefits as well, such as making it more
>convenient to do multi-format LF and join LF.  However afaik, most shops
>doing this would normally have the added overhead of an organized and
>maintained central FldRef file or "Data Dictionary".

I don't see the connection to a 'FldRef' file. Why would this come into it at 
all (other than that it might be a good idea regardless)?


>| Programs using old LFs shouldn't need to be recompiled although
>| the old LFs themselves do (though I'm not clear why they _have_
>| to be other than that's the way DB2/400 was written.)
>
>I don't think they do need recompiled if they use old LFs with the fields
>specified explicitly... ?  Also, the main reason I switched to ChgPF is that
>it's my (partial) understanding IBM does some pointer switching to avoid
>rebuilding the access paths (unless necessary).

Yes, the explicit LFs were the ones I was meaning when I said "old LFs", i.e., 
ones that were effectively unchanged even if recompiled. Also, I agree about 
CHGPF... a great tool -- helps avoid numerous LF re-compiles _especially_ 
explicit LFs and related *pgms. Implicit LFs though can still get formet level 
Id changes after CHGPF and lead to need for *pgm recompiles. Possibly explicit 
LFs as well; I just haven't run into them.

Tom Liotta

-- 
Tom Liotta
The PowerTech Group, Inc.
19426 68th Avenue South
Kent, WA 98032
Phone  253-872-7788 x313
Fax    253-872-7904
http://www.powertech.com


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