Since Release V5R2 there are 2 Query Engines, the classic one (CQE) and the
SQL engine (SQE).
Since Release V5R2 more and more functionality was moved from the CQE to the
SQE.
Beginning with Release 7.1 the transfer was completed.
Already within 7.1 "no SQL" functionality for example using DDS described
logical files in SQL statements, was transferred to the SQE.
With Release 7.2 RCAC (Row and Column Access Control) is included. RCAC is
implemented as additional layer directly in/with the physical files/SQL
tables. RCAC must work independent of the method (SQL, Native I/O,
Query/400, OPNQRYF, UPDDTA, ODBC, JDBC, CPYF, CRTDUPOBJ ...) used to access
the data in these objects. For example independent whether SQL, native I/O,
Query/400 or CPYF is used, the user is only allowed to access the data he is
authorized for.
To get RCAC to work all data access (even native I/O or QUERY/400) must be
performed by the SQE.
Because the old QUERY/400 (which is indeed no SQL) optimizer works
differently than the SQE optimizer, there might be performance problems when
moving to release 7.2 or higher.
That's why a new option, SQE_NATIVE_ACCESS, was added to the QAQQINI file
which allows QUERY/400 or OPNQRYF to use the OLD optimizer (until those
queries are analyzed and new indexes created).
If the SQE_NATIVE_ACCESS method was set, RCAC is not allowed or Queries with
Tables with active RCAC are not executed.
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 Bill
Howie
Gesendet: Thursday, 21.7 2016 20:54
An: midrange-l@xxxxxxxxxxxx
Betreff: SQL optimizer and upgrading from V5R4 to V7R1
Hello all,
We are currently working on a project to upgrade our IBM OS from V5R4 (I
know, I know) to V7R1. One of the things that the consulting company we're
using to help us on this is saying is that we need to pay special attention
to SQL optimization and how it might change between V5R4 and V7R1. Our
opinion among the developers here is that any effect would be minimal
because we do a small amount of embedded SQL in our RPG programs and that
is about it. Wanted to throw it out to the group and see what your
comments were on this. All info is as always appreciated. Thanks!
Bill Howie
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