The selectivity index for height layer varies with seasons and stocking rate.
各高度草层的选择性随季节推移和放牧率不同而发生变化。
The selectivity index of different plant species changes with grazing The selectivity index of different plant species changes with grazing seasons and stocking rate.
山羊对各种植物的选择性指数随放牧季节和放牧率的不同而发生变化。
For comparison, Figure 3 illustrates the access plan where I forced the DB2 optimizer to ignore the index by adding the clause SELECTIVITY 1 to the predicate in the where clause.
为了便于比较，图3显示了通过将SELECTIVITY 1子句添加到where子句的谓词中，强迫db2优化器忽略索引的访问计划。
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