Re: Should I replace all CHAIN, SETLL, and READs to SQL -- RPG400-L

Under the covers, the SQE uses RLA. Why should IBM be the only one to

code an "engine".

The operative words there is "under the covers". These db operations are
occurring at the lowest level of the OS against machine buffers instead of
pulling the entire record through layers of buffers.

As to the I will just recompile that's great if you have 5 day a week shop
and can spend hours on the weekend recompiling 5000 programs because you
added a field to the customer master but if you are running a 7 x 24
operation they frown on that. The bottom line is the same. Every shop I
have ever been in nobody wants to recompile the world. I work in Java shop
for new development (Not me unfortunately) but you watch every day they are
changing the database and nobody even thinks about. Every AS/400 shop.
Absolute agony about making a change to a table.

On Fri, Nov 2, 2012 at 2:18 PM, Nathan Andelin <nandelin@xxxxxxxxx> wrote:

But in return for that 100 millionth of seconds of performance you are

hardwiring the physical view of the table into the program.

I don't have a problem hard-wiring external data structures into programs.
That concern was already addressed by others in the other thread. We have a
CL command / program that reports which programs / service programs may be
affected by changes to tables, and optionally compiles them automatically.
Not a big deal.

Yes, improving I/O performance by a factor of 5-6 is material to me. I've
run benchmarks where RLA was up to 25 times more efficient than SQL. It
depends on what you're doing, and it's good to know what you're doing.

Forget about the I/O performance for a moment and consider the total
resource costs of loading the SQE in every job launched. The SQE is a
substantial (big) run-time environment in and of itself. You could code
*JAVA string objects in all of your RPG programs too, but would you want to
load a JVM for every job?

You have lost your database independence for a few
100 millionth of second performance

You lose database independence by using RPG to begin with.

I have said over and over the whole performance thing starts going
out the window when you begin to consider multiple tables.

Repeating it over and over doesn't make it any more true. Whether you use
SQL or RLA you should know what you're doing and understand the performance
implications. Under the covers, the SQE uses RLA. Why should IBM be the
only one to code an "engine".

-Nathan.

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