I was upgrade V5R3 –> V6R1 in last month,
我們踩到 IBM SQE 的 Bug, 開PMR弄了一個月,才由公司同事找到問題.

There isn’t a problem specifically with the COALESCE function,
 But use COALESCE on columns in Views  then used to join to a table in a query, will cause SQL performance proble.

This SQE  deficiency should be fixed,
rewritting those views can resolve the performance problem . 

Query the SYSVIEWS table to determine if they have other views which use COALESCE,
i.e.:

select system_view_schema,
system_view_name , view_definition
from qsys2/sysviews
where upper(view_definition) like ‘%COALESCE%’