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If your data model is “Insert only,” then you might avoid some concurrency issues,
but most applications are not designed for “Insert only” at the outset.
Your aim is to maximize parallelization while minimizing cost; I discuss this next.
Parallel Processing
Every time you execute DML, you either instantiate a new warehouse or consume a
processing unit from an already running warehouse. Figure 8-12 illustrates the effect of
instantiating a new X-Small warehouse for a single DML statement.
Figure 8-12.
Warehouse single processing unit consumption
Your aim is to utilize every processing unit within every active cluster. When a
warehouse runs, you pay for the whole runtime; costs are not apportioned to each
processing unit executing DML. For maximum efficiency, you must utilize every
processing unit within active warehouses, as shown in Figure 8-13.
Chapter 8
parallelization