elvis的Oracle Lab

Estimator The estimator determines the overall cost of a given execution plan. The estimator generates three different types of measures to achieve this goal: Selectivity This measure represe

What causes Cardinality to be wrong? 1>Data Skews 2>Multiple single column predicates on a table --->>>解决方案为收集扩展统计信息 3>A function wrapped where clause predicate 4>No statistics or Stale St