Hi,
Birgitta, are you saying that some of these won't work with DDS-defined
logicals?
No I said, those enhancements cannot be executed by the CQE and all queries
where DDS described logical files are specified will be rerouted to the CQE.
The SQE can also be used with DDS described logical files, as long as you
only specify the physical files in your SQL statements and as long as there
are no logicals with select/omit clauses built over the physical files you
use.
If there are logical files with select/omit clauses the query will be
rerouted to the CQE, too.
If you set the IGNORE_DERIVED_INDEX option in a copied QAQQINI file to *YES
and use this QAQQINI file in your job with the cl Command CHGQRYA:
CHGQRYA QRYOPTLIB(MYLIB
Now the SQE can be used even if there are logical files with select/omit
clauses. But the query optimizer will ignore all access paths stored in
these logical files.
In this way you may end up by executing the query with the SQE but instead
of using an index a table scan will be performed (because the formerly used
access path is now ignored).
Mit freundlichen Grüßen / Best regards
Birgitta Hauser
"Shoot for the moon, even if you miss, you'll land among the stars." (Les
Brown)
"If you think education is expensive, try ignorance." (Derek Bok)
"What is worse than training your staff and losing them? Not training them
and keeping them!"
-----Ursprüngliche Nachricht-----
Von: rpg400-l-bounces@xxxxxxxxxxxx [mailto:rpg400-l-bounces@xxxxxxxxxxxx] Im
Auftrag von Joe Pluta
Gesendet: Friday, 10. October 2008 12:49
An: RPG programming on the AS400 / iSeries
Betreff: Re: SQL versus READ for sequential processing
David FOXWELL wrote:
Have you an example of enhancements of SQE that cannot be used in this
case? I don't think you mean that certain SQL commands wouldn't execute,
oder?
That's a good question, David. I'm assuming Birgitta is talking about
things like ROLLUP and/or full outer joins. Birgitta, are you saying
that some of these won't work with DDS-defined logicals? I don't have a
problem with the concept, because I am trying to move entirely to DDL,
but it's good to know especially for clients with older legacy systems.
Joe
midrange.com
