One of the issues we face in DB2 today is the unintended changes in SQL Access paths. This can be caused by several factors. One is that when we execute a RUNSTATS utility prior to rebinding packages, statistics can change significantly enough to cause the optimizer to change access paths. Another issue is simply the normal process of application lifecycle. As programs are changed, SQL can change by adding new queries, or changing existing SQL statements. An even bigger issue arises when we apply DB2 maintenance or migrate to new DB2 versions. This is particularly a relevant issue today as many companies are upgrading to DB2 V8. Analyzing your entire system in this case can be a daunting task as you may be dealing with thousands of SQL statements.
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