Poor performance after migrating DB2 from 9.5 to 9.7

Hi guys,

I'm facing terrible performance issues after DB2 migration from V9.5 to V9.7

Here are the details :

#1 Query :
SELECT 1 FROM db2ent.ebcc_customer
where state_prov_county !='' and
legal_entity_no='6222902'
group by country_code
having count( distinct state_prov_county ) > 1
and country_code ='897'"

#2 Server using DB2 V9.5
time db2 "SELECT 1 FROM db2ent.ebcc_customer
where state_prov_county !='' and
legal_entity_no='6222902'
group by country_code
having count( distinct state_prov_county ) > 1
and country_code ='897'"

1
-----------
1

1 record(s) selected.


real 0m0.71s
user 0m0.02s
sys 0m0.01s

#3 Server using DB2 V9.7
time db2 "SELECT 1 FROM db2ent.ebcc_customer
where state_prov_county !='' and
legal_entity_no='6222902'
group by country_code
having count( distinct state_prov_county ) > 1
and country_code ='897'"

1
-----------
1

1 record(s) selected.


real 5m16.82s
user 0m0.02s
sys 0m0.01s

#4 - both dbs use exactly the same configuration parameters (db and instance)

#5 - about stats
I've ran maint routines .
5.1 reorg table - for all tables
5.2. reorg indexes all - for all tables
5.3. runstats with distribution and detailed indexes all - for all tables

#6 - details for server using version 9.7

db2level
DB21085I This instance or install (instance name, where applicable: "dbcctst")
uses "64" bits and DB2 code release "SQL09077" with level identifier
"08080107".
Informational tokens are "DB2 v9.7.0.7", "s121002", "IP23367", and Fix Pack
"7".
Product is installed at "/opt/IBM/db2/V9.7".

oslevel
6.1.0.0

Any ideas ?