Following in the tradition of continued investment in the SQL Query Engine (SQE), IBM i 7.5 includes enhanced parallel processing capability in SQE.
enables the query optimizer to determine the optimal number of tasks with which to run a query. The
optimizer selects this value based on the available processor capacity and the costs to perform aspects of the query.
In IBM i 7.5, SQE is enhanced when *OPTIMIZE is used for parallel execution of a query:
- When a percentage is specified for *OPTIMIZE, SQE will apply the percentage prior to optimization. This will provide the optimizer with more accurate information related to the number of tasks a query may run with.
- Starting in IBM i 7.5, the query engine will dynamically adjust the number of tasks used by queries
running with PARALLEL_DEGREE *OPTIMIZE. As these queries run, the query engine will consider the overall system CPU usage.
- SQE will additionally recognize when the system CPU is reaching a peak level, and automatically reduce the amount of parallel processing used by active queries. The default peak level where this safety adjustment kicks in is 80%, but can be adjusted higher or lower via the new QAQQINI parameter PARALLEL_MAX_SYSTEM_CPU.
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03 May 2022