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Hello David,
Does this parameter have any effect on a file used in an rpg by
embedded sql? I'm looking at a lot of ovrdbf in a clp that uses this
parameter, but without the opnqryf that I'm used to see following it.
I don't think it's possible to share an ODP opened by SQL.
(Unfortunately, I can no longer remember where I heard that.) So unless
I'm mistaken, SHARE(*YES) has no impact on embedded SQL.
As to why a CLP would use SHARE(*YES) without OPNQRYF, there are two
common reasons I've encountered:
a) To improve performance. If you go many years back, when computers
had only kilobytes of memory, the cost (in terms of memory and
performance) of opening a file multiple times was very high. So if you
had multiple programs using the same file, you'd share the ODP so they'd
all share the same file open, improving performance and reducing memory
footprint. IMHO, this is not a good practice today.
b) There was a common misconception that OVRDBF SHARE(*YES) in CL was
the equivalent of the // FILEDISP-SHR in OCL. People translating their
OCL's to CL's when converting from the S/36 would commonly replace
//FILE NAME-FOO,DISP-SHR to OVRDBF FILE(FOO) SHARE(*YES).
The reason at (b) was a misconception. They do /not/ do the same thing
at all. There's no need to do an equivalent of DISP-SHR on OS/400...
Sometimes the calls that follow are to SQLRPGLE programs, which is
the reason for my question. Sometimes the calls are to ordinary RPGs
and there, I don't understand why the programmer has added
share(*yes).
If the file isn't used on an F-spec (by anything that's called within
the scope of the OVRDBF) or a similar mechanism to an F-spec... then I
doubt the SHARE(*YES) is having any impact at all.
More likely the programmer just didn't understand that SHARE(*YES) was
not required, and so kept it when converting from another technology.
Since the share is ignored, it wouldn't have affected the program's
ability to work or not work.
Scott Klement once did an article on OVRDBF. It showed the effect of
combining these commands at different call levels and override
scopes. Does anyone know where I might find that article?
Really? Hmmm.. I don't remember that (but then again, I don't remember
much of anything these days.)
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