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Siebel eBusiness Applications take advantage of DB2 global statement caching. This allows dynamic SQL statements that are reexecuted to bypass the PREPARE phase after the first execution. Dynamic statement caching allows dynamic statements to be prepared once, stored on a global statement cache, then reused many times. The Siebel application is also designed to maximize the reuse of statement caching.
You enabled global statement caching when you set the
Because DB2 saves the cached statement in the Environmental Descriptor Manager (EDM) pool, proper sizing of this pool is very important. For guidance on sizing the EDM pool, see your IBM documentation.
Other system parameters associated with dynamic statement caching are illustrated in Table 18.
After DB2 prepares a SQL statement and places it in the global statement cache, it gets reused. If a customer is performing SQL tuning and it is desirable to force DB2 to prepare and reoptimize a cached statement, the global SQL statement cache must be invalidated.
SQL generated by the Siebel application will be sent to the DB2 host on the z/OS platform through ODBC and the DB2 Call Level Interface (CLI) before the SQL command is processed by DB2. To effectively troubleshoot issues it may be necessary to trace the SQL statement through one or all of these layers. This should normally be done under the guidance of Siebel support personnel who will advise on the most appropriate tracing for the situation. Steps to initiate the tracing at each layer are described below.
|Implementing Siebel eBusiness Applications on DB2 UDB for z/OS and OS/390|