因此，如果统计数据不准确或者过期，或者冲突，优化器会对查询计划中各步骤的成本评估不准确，从而导致糟糕的性能。
Consequently, if the statistics are inaccurate, outdated, or conflicting, the optimizer will create inaccurate estimates for the costs of the steps in a query plan, leading to poor performance.
统计数据冲突：不一致的统计数据可能会导致优化器对成本评估错误，作出错误的访问计划评估决策。
Conflicting statistics: Inconsistent statistics may cause the optimizer to derive the wrong estimated costs and to make the wrong decision on access plan assessment.
目的冲突的情况引出了社会成本最小化的问题。
Our cases of clashing ends bring us to the question of minimizing social costs.
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