800xA event history
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The IM uses Oracle and database tables to store events.
Please read the IM Data Access and Reports User's Guide, 3BUF001094-510 especially Section 9 - Reading Message Logs.
Events stored in an IM Message log can be shown in 800xA Event Lists (using a special configuration - refer to the user's guide), the IM Desktop Event Browser (simple web page) or any other SQL/ODBC compliant client such as MS Excel, MS Access and Oracle's own SQLPlus.
Be sure to learn how event data is split over three tables (MSGLOGxxx, MSGATTRSxxx and MSGVENDORS).
Be aware that default settings only contain table indexes for event time and object name. If you need to search for event attributes (e.g. severity, message text, condition name, etc) performance will drop sharply. This can be countered* by adding additional table indexes (storage requirements inside the tablespaces will increase as a side effect so be prepared to allow additional auto-extend on the database files if you go for this).
*) Unfortunately, the 800xA Event List search engine can not benefit from additional indexes. If you need to use advanced filtering possibly using additional indexes, stay off the 800xA Event List and use some other access method listed above.