SESSCACHE

Typically used only when debugging, the SESSCACHE option controls whether Oracle OLAP creates an Oracle OLAP session cache described in "What is an Oracle OLAP Session Cache?".

Syntax

SESSCACHE = {YES|NO}

Arguments

YES

The session cache is created to hold the data described in "What is an Oracle OLAP Session Cache?".

NO

Oracle OLAP does not read or write to the session cache. When you specify NO, caching does not occur even when you have specified caching by coding a CACHE SESSION statement in the specification for one or more aggmap objects, by setting one or more $VARCACHE properties to SESSION, or by setting the VARCACHE option to SESSION.

Notes

What is an Oracle OLAP Session Cache?

An Oracle OLAP session cache is a special place in memory used to hold:

• All data that was calculated on the fly when an AGGREGATE function executed in the following situations:

  • The specification for the aggregation included a CACHE SESSION.

  • The specification for the aggregation did not include a CACHE SESSION statement, but the variable being aggregated had a $VARCACHE property with the value of SESSION.

  • The specification for the aggregation did not include a CACHE SESSION statement and the variable being aggregated did not have a $VARCACHE property, but the VARCACHE option was set to SESSION.

• The NA values (only) that were calculated when an AGGREGATE function executed and the specification for the aggregation included a CACHE NA statement.

• All data that was calculated when a $NATRIGGER expression executed in the following situations:

  • The variable with the $NATRIGGER property also had a $VARCACHE property with the value of SESSION.

  • The variable with the $NATRIGGER property did not have a $VARCACHE property, but the VARCACHE option was set to SESSION.

There is one internal cache for a session. Cached data is ignored by UPDATE and COMMIT statements. However, once data is cached, Oracle OLAP uses the values in the cache for all calculations except when an AGGREGATE function with the FORCECALC keyword executes. In this case, the FORCECALC keyword specifies that Oracle OLAP recalculate the values.

When a session is terminated, its cache is cleared. To clear the session cache without terminating the session, issue a CLEAR statement.

The effectiveness of a session cache is tracked in the V$AW_CALC dynamic performance view which is discussed in the Oracle OLAP Reference.