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On 28/07/2004, at 4:53 AM, Dave Odom wrote:

Is DB2/400 like VM & MVS DB2, such that when you create tables inside
of DB2 you can't read the data except with SQL and the security inside
of theDB2 engine?

No. That's why our system is called "Integrated". There is no practical difference between SQL tables and DDS files. There are some specialised differences especially between views and logical files but for the most part they can be treated the same.


SQL can be used on DDS files and native I/O can be used on SQL tables.

If that is true, then I prefer SQL for programming
applications, at least from the security aspect.

Again, security is integrated on OS/400. The same data access rules apply to DDS files and SQL tables.


And, if the DB2/400
optimizer is anything like the VM/MVS DB2 optimizer, I'd say that you'll
get better performance with DB2 over the keyed-sequence record-at-a-time
access of the native 400 I/O but usually only IF you have large numbers
of records. The reason for this is because the DB2 Optimizer makes
decisions on how to best get your data, and those decisions may change
day-to-day, whereas the keyed sequence approach goes through keys and
follows much the same path regardless of how circumstances have changed
and may not be the best performer.

It depends. In many cases SQL will be faster but there are other cases where native I/O will be faster. Which is faster is usually a case of:
o processing sets then use SQL
o processing single records then use native I/O
however both methods can be used interchangeably, in the same program, on the same files and for the same purposes.


Regards,
Simon Coulter.
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