mysql 里 delete/update in 语句暴慢无比 优化

通过临时表创建索引用 空间换时间避免频繁读取原表信息

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/*正常写法*/ DELETE from activity where id not in ( SELECT id from activity_data);   /*优化后写法*/ DELETE from activity where id not in (select * from (SELECT id from activity_data) t);

　　

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<!--        update pay_record SET pr_pay_state = #{prPayState} , pr_pay_money = pr_total_money,pr_pay_time = #{prPayTime} WHERE pr_id in(SELECT pr_id FROM pay_record_related WHERE merge_id = #{mergeId})-->         update pay_record SET pr_pay_state = #{prPayState} , pr_pay_money = pr_total_money,pr_pay_time = #{prPayTime} WHERE pr_id in(select * from (SELECT pr_id FROM pay_record_related WHERE merge_id = #{mergeId}) t)