Been meaning to get back to this-un, also. There's no direct connection between specifying field-level DDS in LF and using a Field Reference file. Just that shops that like the one approach probably like the other. (Moot point if you have code-generators doing both, of course.) Afaik, field level described LF won't cause any level checks (unless changed). | -----Original Message----- | From: midrange-l-bounces@xxxxxxxxxxxx | [mailto:midrange-l-bounces@xxxxxxxxxxxx]On Behalf Of Tom Liotta | Sent: Friday, March 12, 2004 10:23 PM | To: midrange-l@xxxxxxxxxxxx | Subject: RE: Level Check Question (jt) | | | 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
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