SQL Turning 案例
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编辑 删除
CBO基数估算错误导致sql低效
原SQL语句如下：select ((v.yvalue * 300) / (u.xvalue * 50)), u.xtime from (select x.index_value xvalue, substr(x.update_time, 1, 14) xtime[@more@]原SQL语句如下：select ((v.yvalue * 300) / (u.xvalue * 50)), u.xtime from (select x.index_value xvalue, substr(x.update_time, 1, 14) xtime from tb_indexs x where x.id in (select min(a.id) from tb_indexs a where a.code = 'HSI' and a.update_time > 20110
