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Tag Archives: Analytic function
利用分析函数改写范围判断自关联查询
最近碰到一个单条SQL运行效率不佳导致数据库整体运行负载较高的问题。 分析、定位数据库的主要负载是这条语句引起的过程相对简单,通过AWR报告就可以比较容易的完成定位,这里就不赘述了。 现在直接看一下这个导致性能问题的SQL语句,其对应的SQL REPORT统计如下: Stat Name Statement Total Per Execution % Snap Total Elapsed Time (ms) 363,741 363,740.78 8 .42 CPU Time (ms) 362,770 362,770.00 8 .81 Executions 1 Buffer Gets 756 756.00 0.00 Disk Reads 0 0.00 … Continue reading