Re: SQL Table Scan Concern.

I think that you might have it backwards.

When using the logical it works as expected, quickly. But using the
Physical, it does a table scan.

Good piece of information... the physical is a non-keyed physical.

Anyway have fun on vaca.


--

Michael Schutte
Admin Professional



Try Bob Evans GRILLING SAUSAGE! This summerâs hottest destination is your
own backyard with Bob Evans Brats and Italian Sausage! For tasty recipes
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midrange-l-bounces@xxxxxxxxxxxx wrote on 07/20/2009 03:31:25 PM:

Several issues. If you have select/omit logicals on the table it could be
dropping into the old query engine. You need to specify in the options

file

ignore the logicals with select/omit.

Going though the logical will do nothing. It will just using the logical

to

get the physical file and then go looking for the indexes it thinks is
correct.

As far as not using the copy in QTEMP did you create the table using SQL
using the generate temp file option? (DECLARE GLOBAL TEMPORARY TABLE) If
not, I don't think SQL would even know the table exists.

I am leaving on vacation so I can't research this further but others can
help you with more details.

On Mon, Jul 20, 2009 at 12:59 PM, DeLong, Eric

<EDeLong@xxxxxxxxxxxxxxx>wrote:

Are there a lot of logicals over that file? While I havenât seen this
myself for a long time, there was a time when the query optimizer would
timeout before it go to search a particular access path, so the

optimizer

would punt (force table scan). I know I saw this prior to SQE...

-Eric DeLong

-----Original Message-----
From: midrange-l-bounces@xxxxxxxxxxxx [mailto:
midrange-l-bounces@xxxxxxxxxxxx] On Behalf Of

Michael_Schutte@xxxxxxxxxxxx

Sent: Monday, July 20, 2009 1:28 PM
To: Midrange Systems Technical Discussion
Subject: SQL Table Scan Concern.


In several web programs, I thought I was being smart by creating tables

in

QTEMP that would contain selection criteria to query against large data
files because we don't have logicals that met my selection criteria.

I

have one that is acting kinda strange. It's not picking a locigal by
company and date over the large data file.

The QTEMP Table only has company and date in the file.

i.e.

001 20090601
001 20090602
001 20090604
001 20090605

Notice that one date is missing. The user wants to be able to select
certain days of the week. ie Weekdays only for an entire month.

Anyway,

I'm trying join this file to a large data file that does have an index

by

company and date.

But VisualExplain is telling me that it's doing a table scan over RTA60
because the cost is better. Which I know that isn't true. If I

replace

RTA60 with the locigal name, it runs as I expect. I hate to use the

logical

in the query because I also have to give the user the ability to run

for

select restaurants (so there's another table in qtemp that has the

user's

selection of restaurants). But nevermind that for now. Just company

and

date I get horrible response time when listing the physical in
the query. Anybody know why?

select a.*
from sar_dates b
join rta60 a on
a.tcono = b.company and a.tdate = b.dateiso

Does a table scan


select a.*
from sar_dates b
join rta60L9 a on
a.tcono = b.company and a.tdate = b.dateiso

Makes use of the RTA60L9 logical.

Thanks in advance for the help.




--

Michael Schutte
Admin Professional



Try Bob Evans GRILLING SAUSAGE! This summerâs hottest destination is

your

own backyard with Bob Evans Brats and Italian Sausage! For tasty

recipes

using Bob Evans grilling sausage, visit http://www.BobEvans.com/Recipes
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