Re: Can I use DDS to create an SQL table name

My problem with the whole "do it because there's improved performance" angle is this:

DDS didn't hurt me, performance-wise, back in 1989 when I first started on the AS/400. I never noticed any performance difference between the S/36 (program-defined) disk access and the new (at the time) external definitions.

But now I'm being told to switch to DDL to perform better over DDS, despite that my computer is 1000 times faster, etc, etc. It just doesn't make a lot of sense.

I do create new tables with DDL, and if I'm doing a major overhaul on an older table, I take the time to update it to DDL. But, not for performance... for the other reasons.

The performance angle just doesn't make much sense.


On 10/25/2014 3:49 PM, Jon Paris wrote:

Agreed that validation on write is great - no argument.

But there is no validation on read and that’s where I disagree with Dan claiming a performance boost. At least as far as RPG native IO is concerned, for SQL access maybe that is the case.

For native I/O bad data will either cause an explosion or (in the case of DS I/O) potentially be ignored. So it really doesn’t matter if reads outnumber writes 25 to 1 because if it blows up once you probably go an fix it! You don’t leave it to blow up again and again.

I find a lot of the DDL performance advantages being touted are not really valid in a real world scenario. Not to say there aren’t other good reasons to use DDL - particularly for new tables - but the cost of switching and the benefits gained are a much finer balance.


Jon Paris

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www.SystemiDeveloper.com