统计视图和REOPT都使优化器可以计算出更精确的基数估计，而后选择一个最佳查询执行计划。
Both statistical views and REOPT allow the optimizer to compute a more accurate cardinality estimate and consequently choose an optimal query execution plan.
然后，优化器可以将输入变量的值与编目统计进行比较，并为谓词计算出一个更好的选择估计。
The optimizer can then compare the input variable values to catalog statistics and compute a better selectivity estimate for predicates.
优化器根据可用的统计信息计算基数的估计值，即预计查询返回的行数。
The optimizer calculates its cardinality estimate — that is, the estimated number of rows returned by the query — based on the statistics available.
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