Peter,
I thought that was the case, that was why I was thinking that SQL views don't have the same limitation as the DDS Logicals. I wanted to confirm my thinking before we start implementing SQL views that are joins across libraries.
Dean Eshleman
Software Development Architect
Everence
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From: MIDRANGE-L <midrange-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Peter Dow
Sent: Monday, November 1, 2021 1:59 PM
To: midrange-l@xxxxxxxxxxxxxxxxxx
Subject: [EXTERNAL] Re: Sql views across libraries and restoring from backup
This email originated outside of Everence. Do not click links or attachments unless you recognize the sender.
Hi Dean,
SQL views are not exactly the same as logical files. They are more like
a stored SQL statement. When you open the view, that's when the SQL
statement is performed.
From https://www.rpgpgm.com/2015/09/build-views-and-views-of-views.html<https://www.rpgpgm.com/2015/09/build-views-and-views-of-views.html>
"When you have a Logical file and you update the "parent" Physical file,
the Logical file is also updated. If you build hundreds of Logical files
it slows downs updates as after the Physical file is updated all of its
Logical files have to be updated too. In my consulting days I have seen
a Physical file with over 200 dependent Logical files.
Views are different. They are not updated when the Physical file, or DDL
table, is updated. Only when the View is used is the data accessed from
the file or table. This leads to one of points Paul made where I wanted
to exclaim "Right on!". You could have many hundreds, nay thousands, of
Views on your IBM i and they would not affect the performance of your
server."
So when a view is restored, the SQL statement is not performed. It does
not matter where the files are until you open the view. As long as you
do that after all restores are completed, it will work fine.
--
*Peter Dow* /
Dow Software Services, Inc.
909 793-9050
petercdow@xxxxxxxxx<mailto:petercdow@xxxxxxxxx>
pdow@xxxxxxxxxxxxxx<mailto:pdow@xxxxxxxxxxxxxx> /
On 11/1/2021 10:33 AM, Dean Eshleman wrote:
Hi,
I was wondering if SQL views that join two files across libraries have the same constraints as join logical files when it comes to what library they should be in so that a restore of the view works successfully. In other words you should place it the library that is restored last alphabetically so that both physicals are there when it is restored. I know that an SQL view shows up on the system as a logical file object, but I also know they have some differences from logical files. TIA
Dean Eshleman
Software Development Architect
Everence
1110 North Main Street
PO Box 483
Goshen, IN 46527
(800) 348-7468 ext. 3528
(574) 533-9515 ext. 3528
[Join our Talent Network]<http://www.everence.com/careers>
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