I am a consultant for customer and whenever handling this, I check the db and onbject
many time you see :
table1 : col1,Col2.....
index1 : col1,col2
index2: col1
index3 : col2
the index 1and 3 i understand : but according my opinion : when doing select tab1 wher col1:xx the index1 can be used
in which case would you need index2 . I immediately drop them
in this case i also check package cache  and see that they query tab1 always as col1:=x and col2=x
and lastused of col2 is mostly never used..  so : could also be dropped
but the word drop is sensitive for the customer and they do not allow the drop
can you give your opinion what you would do..
the total of indexes to be dropped would be about 250 indexes..
you see the overhead to maintain - and space usage ?

------------------------------
Thanks for all answers
Best Regards,
Guy Przytula
------------------------------

#Db2

Hi Guy,

it's all in the web! You just have to find it or a person, who knows the right key words and hase the right filter bubble on Google. :-)

Have a look at Embers blog: Multiple Index Regression Analysis

Scott Hayes has done some presentations on that topic too. Hint Sage Advice, part 4

Kind regards

------------------------------
Roland Schock
Distinguished Engineer
ARS Computer und Consulting GmbH
Muenchen
------------------------------

Original Message:
Sent: Thu May 07, 2020 05:09 AM
From: Guy Przytula
Subject: unused indexes

I am a consultant for customer and whenever handling this, I check the db and onbject
many time you see :
table1 : col1,Col2.....
index1 : col1,col2
index2: col1
index3 : col2
the index 1and 3 i understand : but according my opinion : when doing select tab1 wher col1:xx the index1 can be used
in which case would you need index2 . I immediately drop them
in this case i also check package cache  and see that they query tab1 always as col1:=x and col2=x
and lastused of col2 is mostly never used..  so : could also be dropped
but the word drop is sensitive for the customer and they do not allow the drop
can you give your opinion what you would do..
the total of indexes to be dropped would be about 250 indexes..
you see the overhead to maintain - and space usage ?

------------------------------
Thanks for all answers
Best Regards,
Guy Przytula
------------------------------

#Db2