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order_date,
nation_name,
region_name )
VALUES ( s.customer_key,
s.customer_name,
s.order_key,
s.order_date,
s.nation_name,
s.region_name );
Figure 8-17 shows the effect of changing the warehouse size for the same workload
MERGE
into a consistent reset target core table.
Figure 8-17.
Warehouse effect on MERGE
note the Spills to Disk value for X-Small and Small warehouses.
Having set the warehouse performance baseline, let’s now segment the target
core table.
Core Table Segmentation
Identifying the target core table’s clustering key is crucial for developing a parallelization
strategy as the target core table clustering key lead attribute is usually the prime
candidate to segment the target core table. You are looking for a low-cardinality
manageable range of attributes matching the most commonly used query predicates.
Chapter 8
parallelization