加入vs多个数据副本：性能
I was just reading http://s.niallkennedy.com/blog/uploads/flickr_php.pdf about Flickr's infrastructure and this is what it said.
我刚刚阅读http://s.niallkennedy.com/blog/uploads/flickr_php.pdf关于Flickr的基础设施，这就是它所说的。
JOIN’s are slow
• Normalised data is for sissies
• Keep multiple copies of data around
• Makes searching faster
Is it true or its just their way of managing their DBs? If I just looking for performance that is it better to not normalise?
是真的还是只是他们管理数据库的方式？如果我只是寻找性能，那么最好不规范化？
1 个解决方案
#1
3
Joins become a performance issue on large data sets. It's not something to worry about if you are not experiencing slowness issues. There are big advantages to normalized data, but nobody ever goes to fifth normal form. Typical is second or third normal form.
联接成为大型数据集的性能问题。如果您没有遇到缓慢问题，那就不用担心了。标准化数据有很大的优势，但没有人会达到第五范式。典型的是第二或第三范式。
When you have performance issues, then you should consider de-normalizing what you have and making copies of data optimized for retrieval. Especially data that doesn't change.
当您遇到性能问题时，您应该考虑对所拥有的内容进行反规范化，并为检索优化数据副本。特别是不会改变的数据。
Flickr probably has few updates, so there is minimal overhead in keeping multiple copies of data. They also have the luxury of eventual consistency, data doesn't have to replicate in real time.
Flickr可能只有很少的更新，因此保留多个数据副本的开销很小。他们还拥有最终的一致性，数据不必实时复制。
更多相关文章
- MySQL多个连接到付款数据的日历表
- MYSQL 导入53M数据报错
- 解决Navicat数据传输问题:The‘InnoDB’feature is disabled; yo
- 项目实战7—Mysql实现企业级数据库主从复制架构实战
- Mysql数据库的打开和关闭
- oracle、mysql、db2三大数据库分页方法的整理
- MySQL---数据库从入门走向大神系列(三)-修改数据库编码/DOS窗口
- MySQL] 行列转换变化各种方法实现总结（行变列报表统计、列变行数
- java实现定时备份mysql数据库-----已通过测试