Adaptive Server version 15.0 uses more procedure cache for several reasons. Most important reasons are:
Adaptive Server version 15.0 query processing engine looks for more ways to optimize the query to run better
Adaptive Server version 15.0 execution engine avoids materialization of work table and tends to evaluate aggregations in memory as much as possible.
The data change counters maintained for the function datachange() allocates memory from procedure cache. The partition condition tree is cached in the procedure cache. Partition boundary values are allocated in the procedure cache resulting in a required increase in procedure cache resources.
In Adaptive Server 15.0, a new configuration parameter max repartition degree has been added. This parameter controls the maximum degree to which an intermediate data stream can be re-partitioned. The default value of this parameter is set to 1, which means that this parameter is not set and is bound by the number of online engines configured for Adaptive Server. For a query with a large number of tables Adaptive Server version 15.0 can put an increased demand on auxiliary scan descriptors.
Set the value of max repartition degree to a value lower than the number of engines to decrease such resource usage. Also, configuring a larger value for the auxiliary scan descriptor pool may be required.
Adaptive Server version 15.0 avoid worktable materialization and Adaptive Server version 15.0 may incur more resources in auxiliary scan descriptors.
During upgrade, max memory is increased by Adaptive Server if the new total logical memory is greater than max memory. The new value of max memory is set to the new value of total logical memory.
During upgrade, number of open partitions is set to the same value as number of open indexes resulting in increased memory usage. An open partition requires approximately 950 bytes.
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