Re: SQL Equivalent of CRTLF -- RPG400-L

+++++1

In the ACS Run SQL scripts action there are a couple examples related to advised indexes - one is an automated processor for advised indexes that takes 2 steps - one is to create any advised indexes that have been used by a Maintained Temporary Index more than a certain number of times (500 in the example), the other is to delete indexes that older than some time span (7 days in the example) and haven't been used at least certain number of times (500 again) in that period.

The example shows how to create an SQLprocedure to do thisI presented a possible RP

Another example has statements to analyze advice since the last IPL - these can help decide if you really need to create something advised. I saw some things that might mean ignore the advice - like last date MTI used is the minimum timestamp, well, do any of us have something used on 0001-01-01-00.00.00.000000?

And do YOU want to be the one creating indexes for one of IBM's products? I think I saw some of them in there, too.

These tools are examples of things that can be used especially by a person in the role of DBE - database engineer, a role IBM has been talking about the last few years.

Regards
Vern

On 10/19/2020 1:39 AM, Birgitta Hauser wrote:

It will tell you what indexes you have to create...

... but be careful!
Do not create all advised indexes. Decide wisely!
Check how often they are advised for which query they are advised. Creating hundreds of indexes for big tables with hundreds of millions of rows is not a good idea. Each index slows down performance when inserting/updating or deleting rows in a table.
Index Access on small tables may be (slightly) slower than a table scan.
Indexing and Statistics Strategies are a little more complex then just creating advised indexes.

I'd recommend to read the following white paper from Mike Caine and Kent Milligan:
Indexing and Statistics Strategies
https://www.ibm.com/support/pages/sites/default/files/inline-files/$FILE/indexing%20and%20statistics%202011.pdf

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!"
„Train people well enough so they can leave, treat them well enough so they don't want to.“ (Richard Branson)

-----Original Message-----
From: RPG400-L <rpg400-l-bounces@xxxxxxxxxxxxxxxxxx> On Behalf Of Reeve
Sent: Montag, 19. Oktober 2020 05:36
To: RPG programming on IBM i <rpg400-l@xxxxxxxxxxxxxxxxxx>
Subject: Re: SQL Equivalent of CRTLF

Greg, I highly recommend looking into the Index Advisor. It will tell you what indexes you have to create...and the IA will do it with a click.

I code against tables/PF’s and let the IA tell me what I have to create for performance. I still use LF’s a bit but not in any new code I’ve written in years.

-Reeve

On Fri, Oct 16, 2020 at 07:46 Greg Wilburn <gwilburn@xxxxxxxxxxxxxxxxxxxxxxx>
wrote:

I've been using SQL I programs and to create views for quite some time.
I'm trying to force myself away from DDS.

So I created a new table with SQL... now I need to create a subset of
that table by way of a logical file (I want to use RPG Native access
in my program), which can also be updated.

Is there a simple way to create a view of my table that contains all
columns "where" one of the columns is blank?

My current take on DDL versus DDS is that DDS is much, much easier and
faster to use.
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