SQL Views cannot be keyed, because the Query Optimizer decides if or which
access path (key constraint, SQL index or DDS described logical file) is
taken. The optimizer may even use multiple indexes for the same query or use
today and index which is no longer used tomorrow.
SQL indexes were enhanced in Release 6.1 so new key columns can be created
based on SQL operations and/or scalar functions. It is also possible to add
where conditions to an SQL index.
While an SQL index cannot be specified in an SQL statement, it is possible
using the index in conjunction with native I/O like any keyed logical file.
An MQT (Materialized Query Table) is an table based on an Select-Statement,
that could be used by the SQL query optimizer like an SQL index (if we allow
the optimizer to use MQTs). Because an MQT is a table, additional indexes
(and views) can be built over an MQT.
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: MIDRANGE-L [mailto:midrange-l-bounces@xxxxxxxxxxxx] Im Auftrag von Jeff
Young
Gesendet: Friday, 29.4 2016 16:41
An: Midrange Systems Technical Discussion
Betreff: Keyed SQL View
V7R2
I seem to recall discussions in the past regarding creating a keyed view,
but can not find anything in the SQL reference manual regarding it.
Can this be done?
If so, any references would be appreciated.
Jeff Young
Sr. Programmer Analyst
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