Re: Is this an SQL problem or quirk

Thanks for your reply Charles
It may seem that either, we both need new glasses, or its some mass
hallucination between us, but the LONG story was
1/. we thought that he had a weird version of the custadrp file (not true)
2/. he was signed onto a different box (not true - the file APTSCAN ONLY
exists in my library on the development box)
3/. we changed the SQL to ONLY look at the files in the named libraries
the result was still the same.
Run the SQL signed on as me - no problems, the results were as expected.
Run the SQL signed on as him (at the same terminal in fact, different
sessions) the weird results are displayed
In all circumstances we copied the SQL statement and pasted the same SQL
statement into each sessions STRSQL
So we can definitely say that the SQL statement is NOT the problem


Alan Shore
Programmer/Analyst, Distribution
E:AShore@xxxxxxxxxxx
P:(631) 200-5019
C:(631) 880-8640
"If you're going through Hell, keep going" - Winston Churchill

midrange-l-bounces@xxxxxxxxxxxx wrote on 02/10/2009 10:56:22 AM:

This is on the same machine right?

Double check his SQL. Try the statement again

It sounds as if he missed the where when he copied & pasted.

Are you still getting the same results?

Charles


On Tue, Feb 10, 2009 at 10:44 AM, Alan Shore <AlanShore@xxxxxxxx> wrote:

Thanks for your reply Charles, but the SQL statement he ran was the one
that I had used. He copied and pasted it into his STRSQL session. Hence

our

quandary.


Alan Shore
Programmer/Analyst, Distribution
E:AShore@xxxxxxxxxxx
P:(631) 200-5019
C:(631) 880-8640
"If you're going through Hell, keep going" - Winston Churchill

midrange-l-bounces@xxxxxxxxxxxx wrote on 02/10/2009 10:28:42 AM:

Alan,

The result set (but not necessarily the order of that result set)
should always be the same no matter what query engine or options are
in effect.

While it's possible you've found a bug, I'd think it more likly that
your associate's SQL statement was not correct.

Can you post it?

Charles

On Tue, Feb 10, 2009 at 9:30 AM, Alan Shore <AlanShore@xxxxxxxx>

wrote:

Good morning list
For those faint of heart, please take your nitroglycerine pills now.

The article I need to ask you about can be found at
http://www.itjungle.com/fhg/fhg041608-story01.html

First some groundwork
On our customer file within the 2 address lines we have addresses
containing the words
"APT "
APT. "
"UNIT "
etc

The project is to attempt to "pull" this data out and place into a

separate

field. I came up with the following idea
I have a file (APTSCAN) with one 12 character field (APTSCANDEF)

containing

(at the moment) the following data, % characters included
%APT %
%APT #%
%APT. #%
%APT.%
%BLDG%
%DEPARTMENT%
%DEPT %
%FLOOR %
%FLR %
%FLR.%
%P O BOX%
%P.O. BOX%
%PO BOX%
%PO.BOX%
%POBOX%
%ROOM %
%UNIT %
%UNIT #%
I then ran the following SQL statement

SELECT * FROM custadrp a, APTSCAN b
WHERE a.CADD1 like b.APTSCANDEF or
a.CADD2 like b.APTSCANDEF

and it worked perfectly. All the relevant customer records were

displayed.

I then sent the above SQL to an associate who has to do something

similar.

He ran the same sql and the results were COMPLETELY different
He had displayed ALL the customer records, with each customer record

being

displayed once for each record on the APTSCAN, even if the

customers

data

did or did not contain what was in the APTSCAN file.
To cut a LONG story short, my associate has read and followed the

above

article.
The changes he had made to his SQL query options file was as follows

(this

is from an e-mail he sent to me)
Quote
There were 2 difference in my SQL query options file. The first was
MESSAGES_DEBUG. Mine was set to *YES, which would force SQL to

always

dump

the debug messages to the job log. I do not see this causing the

results we

saw.

The second difference was IGNORE_DERIVED_INDEX. It defaults to *NO.

Mine

was set to *YES. According to the text in the file, it says....

Allows SQE to process the query even when a mapped key index or

select

omit

index exists over a table in the query. SQE will ignore the derived

index

(s) and continue. QQVAL: *DEFAULT--The default value is set to *NO.
*YES--Allow the SQE optimizer to ignore the derived index and

process

the

query. The resulting query plan will be created without any regard

to

the

existence of the derived index(s). *NO--Do not ignore the derived

index. If

a derived index exists CQE will process the query.

I tested my config by setting this back to *DEFAULT and the query

performed

as normal.

From my understanding, there are 2 query engines present on the

iSeries,

SQE and CQE. CQE is for "legacy" type queries using logicals

containing

Select/Omits. CQE is also very bad when it comes to performance.

Setting

IGNORE_DERIVED_INDEX to *YES forces all queries to always use the

newer

engine (gaining better performance). My understanding was: if your

SQL

statements do not specifically refer to a logical with Select/Omits,

you

are fine to do this. This is why I always use the physical file name

in

my

statements and let the optimizer figure out the underlying details.
End Quote

The questions that come to mind are
1. Are we missing any PTF's?
2. Is this a problem that should be reported to IBM
If anyone has some ideas and/or insight as to why this is happening.

It

would be MUCH appreciated
P.S. I have also sent this same inquiry to Ted Holt, the author of

the

above article



Alan Shore
Programmer/Analyst, Distribution
E:AShore@xxxxxxxxxxx
P:(631) 200-5019
C:(631) 880-8640
"If you're going through Hell, keep going" - Winston Churchill
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