DB2 - L

Hi All!
 I have been asked by a couple of people about the current usage, acceptance, stability and usefullness of the latest update of the FTB feature: Support for non-unique keys.
I know a lot of people were bitten badly by the first generation of FTB and so was wondering "How's FTB 2.0 looking?"

 Looking forward to hearing any stories good or bad!
Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------

Hello Roy,
This is one of those features that really gets people talking, but it's kind of a set and forget feature. After all, there is no real tuning going on and almost nothing to do with it except monitoring. Measurements of savings are difficult to do. I just checked a very busy production data sharing group at V12M508. Significant use of FTB across a variety of indexes unique and not unique. No issues. Yes, early on we turned it off due to chatter about various problems. We have since silently enabled it, and no one noticed. I keep a steady eye on the performance of critical application processes (thousand of transactions per second) and while I've seen a trend of improved performance, I cannot put my finger on exactly what it is CPU, DASD, Cache, FTB, etc. I can correlate performance improvements to CPU and DASD upgrades, but the subtle little surprises along the way I just can't nail down. You would think I can look at index getpages per transaction but at this level of activity and shared pools it's just not possible. All I can say is significant use proven via a DISPLAY STATS(IMU) command and no apparent issues.
Cheers,
Dan


Original Message:
Sent: 3/16/2022 8:51:00 AM
From: Roy Boxwell
Subject: Db2 z/OS usag of FTB non-unique feature

Hi All!
 I have been asked by a couple of people about the current usage, acceptance, stability and usefullness of the latest update of the FTB feature: Support for non-unique keys.
I know a lot of people were bitten badly by the first generation of FTB and so was wondering "How's FTB 2.0 looking?"

 Looking forward to hearing any stories good or bad!
Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------

Hi Dan,
 Thanks for the data that is very very helpful indeed!

Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------

Original Message:
Sent: Mar 16, 2022 09:45 AM
From: Daniel Luksetich
Subject: Db2 z/OS usag of FTB non-unique feature

Hello Roy,
This is one of those features that really gets people talking, but it's kind of a set and forget feature. After all, there is no real tuning going on and almost nothing to do with it except monitoring. Measurements of savings are difficult to do. I just checked a very busy production data sharing group at V12M508. Significant use of FTB across a variety of indexes unique and not unique. No issues. Yes, early on we turned it off due to chatter about various problems. We have since silently enabled it, and no one noticed. I keep a steady eye on the performance of critical application processes (thousand of transactions per second) and while I've seen a trend of improved performance, I cannot put my finger on exactly what it is CPU, DASD, Cache, FTB, etc. I can correlate performance improvements to CPU and DASD upgrades, but the subtle little surprises along the way I just can't nail down. You would think I can look at index getpages per transaction but at this level of activity and shared pools it's just not possible. All I can say is significant use proven via a DISPLAY STATS(IMU) command and no apparent issues.
Cheers,
Dan


Original Message:
Sent: 3/16/2022 8:51:00 AM
From: Roy Boxwell
Subject: Db2 z/OS usag of FTB non-unique feature

Hi All!
 I have been asked by a couple of people about the current usage, acceptance, stability and usefullness of the latest update of the FTB feature: Support for non-unique keys.
I know a lot of people were bitten badly by the first generation of FTB and so was wondering "How's FTB 2.0 looking?"

 Looking forward to hearing any stories good or bad!
Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------

HI Dan (and Roy)
I agree with Dan.  FTB is a feature that we have enabled and then ignored because it has caused no issue.  I agree it one of those things that is hard to measure the benefit.  I have assumed it was beneficial
And I have not really thought about FTB in a while...

Dan, can I ask what you look at when you review DISPLAY STAT(IMU) ??   
The output is the list of indexes using FTB with the amount of memory being used.  Sorted with indexes using the most memory at top of the list.

Is it significant if the memory usage is really high?  (what is really high?).... or what if the memory usage is trivially low?  Does that matter?
Or... do we review and see how memory usage changes over time...?  

> Basically... I think the output tends to consistently display the top few indexes using FTB ... and the ones using the most memory seem to use the same amount... and the same ones tend to appear at the top all the time... 
>> and in my cases... the indexes I see at  the top are familiar indexes.  I know they are popular...

just curious
thank
Brian


------------------------------
Brian Laube Manulife Financial

Db2 Z DBA (mostly)
------------------------------

Original Message:
Sent: Mar 16, 2022 09:45 AM
From: Daniel Luksetich
Subject: Db2 z/OS usag of FTB non-unique feature

Hello Roy,
This is one of those features that really gets people talking, but it's kind of a set and forget feature. After all, there is no real tuning going on and almost nothing to do with it except monitoring. Measurements of savings are difficult to do. I just checked a very busy production data sharing group at V12M508. Significant use of FTB across a variety of indexes unique and not unique. No issues. Yes, early on we turned it off due to chatter about various problems. We have since silently enabled it, and no one noticed. I keep a steady eye on the performance of critical application processes (thousand of transactions per second) and while I've seen a trend of improved performance, I cannot put my finger on exactly what it is CPU, DASD, Cache, FTB, etc. I can correlate performance improvements to CPU and DASD upgrades, but the subtle little surprises along the way I just can't nail down. You would think I can look at index getpages per transaction but at this level of activity and shared pools it's just not possible. All I can say is significant use proven via a DISPLAY STATS(IMU) command and no apparent issues.
Cheers,
Dan


Original Message:
Sent: 3/16/2022 8:51:00 AM
From: Roy Boxwell
Subject: Db2 z/OS usag of FTB non-unique feature

Hi All!
 I have been asked by a couple of people about the current usage, acceptance, stability and usefullness of the latest update of the FTB feature: Support for non-unique keys.
I know a lot of people were bitten badly by the first generation of FTB and so was wondering "How's FTB 2.0 looking?"

 Looking forward to hearing any stories good or bad!
Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------

Brian,
All I do is look at the index names. I know which applications and tables are the most active and so when I do not see an index that I know (based upon activity as demonstrated in Db2 accounting reports) should be using FTB and they are not then I investigate as to why. The amount of memory used is irrelevant to me just whether or not an index is utilizing the feature.
Dan


Original Message:
Sent: 3/16/2022 12:17:00 PM
From: Brian Laube
Subject: RE: Db2 z/OS usag of FTB non-unique feature

HI Dan (and Roy)
I agree with Dan.  FTB is a feature that we have enabled and then ignored because it has caused no issue.  I agree it one of those things that is hard to measure the benefit.  I have assumed it was beneficial
And I have not really thought about FTB in a while...

Dan, can I ask what you look at when you review DISPLAY STAT(IMU) ??   
The output is the list of indexes using FTB with the amount of memory being used.  Sorted with indexes using the most memory at top of the list.

Is it significant if the memory usage is really high?  (what is really high?).... or what if the memory usage is trivially low?  Does that matter?
Or... do we review and see how memory usage changes over time...?  

> Basically... I think the output tends to consistently display the top few indexes using FTB ... and the ones using the most memory seem to use the same amount... and the same ones tend to appear at the top all the time... 
>> and in my cases... the indexes I see at  the top are familiar indexes.  I know they are popular...

just curious
thank
Brian


------------------------------
Brian Laube Manulife Financial

Db2 Z DBA (mostly)
------------------------------

Original Message:
Sent: Mar 16, 2022 09:45 AM
From: Daniel Luksetich
Subject: Db2 z/OS usag of FTB non-unique feature

Hello Roy,
This is one of those features that really gets people talking, but it's kind of a set and forget feature. After all, there is no real tuning going on and almost nothing to do with it except monitoring. Measurements of savings are difficult to do. I just checked a very busy production data sharing group at V12M508. Significant use of FTB across a variety of indexes unique and not unique. No issues. Yes, early on we turned it off due to chatter about various problems. We have since silently enabled it, and no one noticed. I keep a steady eye on the performance of critical application processes (thousand of transactions per second) and while I've seen a trend of improved performance, I cannot put my finger on exactly what it is CPU, DASD, Cache, FTB, etc. I can correlate performance improvements to CPU and DASD upgrades, but the subtle little surprises along the way I just can't nail down. You would think I can look at index getpages per transaction but at this level of activity and shared pools it's just not possible. All I can say is significant use proven via a DISPLAY STATS(IMU) command and no apparent issues.
Cheers,
Dan


Original Message:
Sent: 3/16/2022 8:51:00 AM
From: Roy Boxwell
Subject: Db2 z/OS usag of FTB non-unique feature

Hi All!
 I have been asked by a couple of people about the current usage, acceptance, stability and usefullness of the latest update of the FTB feature: Support for non-unique keys.
I know a lot of people were bitten badly by the first generation of FTB and so was wondering "How's FTB 2.0 looking?"

 Looking forward to hearing any stories good or bad!
Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------

Great answer Dan.  
I understand that answer and it makes sense.  I can review with that perspective!

thanks again
Brian

------------------------------
Brian Laube Manulife Financial

Db2 Z DBA (mostly)
------------------------------

Original Message:
Sent: Mar 16, 2022 01:00 PM
From: Daniel Luksetich
Subject: Db2 z/OS usag of FTB non-unique feature

Brian,
All I do is look at the index names. I know which applications and tables are the most active and so when I do not see an index that I know (based upon activity as demonstrated in Db2 accounting reports) should be using FTB and they are not then I investigate as to why. The amount of memory used is irrelevant to me just whether or not an index is utilizing the feature.
Dan


Original Message:
Sent: 3/16/2022 12:17:00 PM
From: Brian Laube
Subject: RE: Db2 z/OS usag of FTB non-unique feature

HI Dan (and Roy)
I agree with Dan.  FTB is a feature that we have enabled and then ignored because it has caused no issue.  I agree it one of those things that is hard to measure the benefit.  I have assumed it was beneficial
And I have not really thought about FTB in a while...

Dan, can I ask what you look at when you review DISPLAY STAT(IMU) ??   
The output is the list of indexes using FTB with the amount of memory being used.  Sorted with indexes using the most memory at top of the list.

Is it significant if the memory usage is really high?  (what is really high?).... or what if the memory usage is trivially low?  Does that matter?
Or... do we review and see how memory usage changes over time...?  

> Basically... I think the output tends to consistently display the top few indexes using FTB ... and the ones using the most memory seem to use the same amount... and the same ones tend to appear at the top all the time... 
>> and in my cases... the indexes I see at  the top are familiar indexes.  I know they are popular...

just curious
thank
Brian


------------------------------
Brian Laube Manulife Financial

Db2 Z DBA (mostly)

Original Message:
Sent: Mar 16, 2022 09:45 AM
From: Daniel Luksetich
Subject: Db2 z/OS usag of FTB non-unique feature

Hello Roy,
This is one of those features that really gets people talking, but it's kind of a set and forget feature. After all, there is no real tuning going on and almost nothing to do with it except monitoring. Measurements of savings are difficult to do. I just checked a very busy production data sharing group at V12M508. Significant use of FTB across a variety of indexes unique and not unique. No issues. Yes, early on we turned it off due to chatter about various problems. We have since silently enabled it, and no one noticed. I keep a steady eye on the performance of critical application processes (thousand of transactions per second) and while I've seen a trend of improved performance, I cannot put my finger on exactly what it is CPU, DASD, Cache, FTB, etc. I can correlate performance improvements to CPU and DASD upgrades, but the subtle little surprises along the way I just can't nail down. You would think I can look at index getpages per transaction but at this level of activity and shared pools it's just not possible. All I can say is significant use proven via a DISPLAY STATS(IMU) command and no apparent issues.
Cheers,
Dan


Original Message:
Sent: 3/16/2022 8:51:00 AM
From: Roy Boxwell
Subject: Db2 z/OS usag of FTB non-unique feature

Hi All!
 I have been asked by a couple of people about the current usage, acceptance, stability and usefullness of the latest update of the FTB feature: Support for non-unique keys.
I know a lot of people were bitten badly by the first generation of FTB and so was wondering "How's FTB 2.0 looking?"

 Looking forward to hearing any stories good or bad!
Cheers!

------------------------------
Roy Boxwell
Software Engineering GmbH
------------------------------