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Optimization Tips | Tip #28: OR-queries should match as much as possible as soon as possible

分类: 文章 • 2025-02-22 13:19:22

OR查询完全和AND相反,试着先放多包含的,MongoDB不得不每次匹配时检查是否包含数据集的一部分在文档中.

如果我们按照顺序像AND查询一样,我们不得不为每个子句检查一下文档.

Optimization Tips | Tip #28: OR-queries should match as much as possible as soon as possible

Figure 3-7 这个矩形是个集合,色彩较暗的是集合的一部分必须每次进行搜索的,首先搜索C,迫使我们在每次后来的查询中进行大规模的查询.


如果改为下面这样,我们尽可能多的匹配集合.


Optimization Tips | Tip #28: OR-queries should match as much as possible as soon as possible


先查询大数据集,这样我们就限制了以后的查询空间!


原版书<<50 Tips and Tricks for MongoDB Developers>> 地址:http://oreilly.com/catalog/0636920019893

皮皮书屋下载地址：http://www.ppurl.com/2011/05/50-tips-and-tricks-for-mongodb-developers.html

本书的所有翻译地址:http://blog.****.net/crazyjixiang/article/category/858638

翻译目的:MongoDB资料国内很少，书就更不必说了,借助对MongoDB的理解为大家做点贡献，如果有翻译有误的地方请指正,不能误入子弟,谢谢！

译者:Crazybaby






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