RE: Logical File or OPNQRYF or any other way ? - Legacy

[Chris Bipes <chris.bipes@xxxxxxxxxxxxxxx>]

One must remember that if multiple LF have the same key fields in the same
order, they share the access path.  The access path or should I call it, "
Index", is really separate from the View but the LF ties them together in
the DB Manager so we never need to worry about it.  DDS allows you to create
views with indexes while SQL does not.  Hmmm! Which is more flexible?  Under
the covers of the DBMS they are all the same stuff.  Access path sharing
happens whether you know it or not.

For instance create a file with a couple of fields, A, B, C, and D.

Create an index I1 using A, B, and C.

Create an index I2 using A and B.

Not that I2 will always present the data in the same order as I1 if you
create I1 before I2 cause they will share the access path.

I do not believe in creating a new View for each program but do believe in
making sure each LF has it's own view and not share with the PF.  Makes it
easy for the application programmer to add the field and a maintenance
programmer can later add it to the logicals and re-compile everything.

Do like the flexibility of imbedded SQL also.  There is a time and a place
for each method.  Up front planning is always the best approach.

Chris Bipes

-----Original Message-----
> Please, do not go on that path!!!!
> You will create a magnitude of different logicals with all kinds of nasty
> record-formats not representing all the fields in the PF record-format.
> You get your self in serious problems determining what
logical/record-format
> to use when you have to create a new function over the Db....Yeah, the
> accesspath exist. Noooo, the fields needed are not in this
record-format!!!
> What to do???? Create a other LF??
> I've seen laaaaarge systems with numerous logicals with exact the same
> access-pathbut different records-formats because they had to decide
> every-time 'for the sake of not having to recompile and to distribut half
of
> the application running in more than 50 countries' to create a new logical
on
> the same path but with again an different record-format.
> There system would have been a lot nicer/smaller/faster when they had kept
> them self to the 'First lesson of databasedesign'. One PF has One
> record-format! Every LF uses this record-format!
> When one PF got more than 10 LF's......You have to determine if your Db
> design is still correct!