About me:Oracle ACE pro,optimistic,passionate and harmonious. Focus on ORACLE,MySQL and other database programming,peformance tuning,db design, j2ee,Linux/AIX,Architecture tech,etc
全部博文（191）
发布时间：2020-08-31 16:00:09
直方图与绑定变量问题是困扰SQL性能优化的一个典型问题：一方面绑定变量是为了让执行计划共享，从而减少或避免解析，但是如果一个列分布不均，传入不同的值最佳执行计划应该不一样，比如当status=’INVALID’的时候最佳执行计划是走索引，当status=’VALID’时候最佳执行计划是要求全表扫描，遇到这种情况，必须要再次窥视传入的绑定变量值，才能走正确执行计划，因此，11G引入了Adaptive Cursor Sharing(ACS)来解决这个问题，但是因为BUG多，一般情况下生产库是建议关闭的。那么还能不能解决这个问题呢？在11.2及之后答案是肯定的。在11.2的时候，我们使用SQL PATCH来解决，这个类似SQL PROFILE。......【阅读全文】
吻的感觉适2025-07-18 23:11
https://txc.qq.com/products/762795/blog/2019636
https://txc.qq.com/products/762801/blog/2019637
https://txc.qq.com/products/762763/blog/2019638
https://txc.qq.com/products/762772/blog/2019639
https://txc.qq.com/products/762790/blog/2019641
https://txc.qq.com/products/762758/blog/2019640
https://txc.qq.com/products/762786/blog/2019642
https://txc.qq.com/products/762782/blog/2019643
https://txc.qq.com/products/762757/blog/2019644
https://txc.qq.com/products/762805/blog/2019645
https://txc.qq.com/products/762785/blog/2019647
https://txc.qq.com/products/762815/blog/2019646
https://txc.qq.com/products/762787/blog/2019648
https://txc.qq.com/products/762799/blog/2019649
https://txc.qq.com/products/762775/blog/2019650
https://txc.qq.com/products/762759/blog/2019651
https://txc.qq.com/products/762770/blog/2019652
https://txc.qq.com/products/762855/blog/2019654
