Re: RPG SQL and Cursors

On 11/18/2010 5:32 PM, Alan Campin wrote:

As usual with the AS/400 everyone in these discussions is ignoring the 300
pound gorilla in the room, database independence.

When you use RLA, unless you externalize your I/O somehow (which almost no
one know how to do and won't use it even if you did), you are bringing the
entire record into the program which in effect, locks the table to change.

That means the next time you need to change the table you have to recompile
every program that uses it and very quickly no wants to recompile 500
programs so they start creating extension tables or reusing fields or god
knows what.

This is not true.

First: recompiling is not that bad. It depends on how many programs you have and how they access the file. The better your architecture, the fewer programs access the file and the easier it is to accommodate changes.

Second, even if you do access the file in a lot of programs, you can achieve EXACTLY the same level of data independence through a logical view.

If you are using SQL and bringing only what you need that table is still
independent. You can add additional data elements and not have to recompile
the entire world.

And that's ALL you can do. You can't move fields to other tables, you can't rename them, and you can't change their fundamental characteristics. And as I noted above, using a logical makes it very easy to add a field without having to "recompile the entire world".

So do you really want to save a few billionth of a second by using RLA and
then spend god knows how many programmer hours trying to get around the fact
that you have hardwired your database into every program in the system?

Hyperbole in defense of a bad architecture, which has nothing to do with the database. Like anything else, RLA vs SQL is a business decision, not a religious one. A good architect can use RLA effectively and create a system be every bit as easy to maintain as a wholly SQL one - and it will run faster and better. A bad architect, on the other hand, will create junk no matter what tool he uses.

Joe