是什么使对OLAP多维数据集/数据集市和类似数据结构的访问比对关系数据库的访问速度更快? [英] What makes access to OLAP Cubes / Datamarts and similar datastructures, faster than to relational databases?
问题描述
是什么使对OLAP Cubes/Datamart和类似数据结构的访问比对关系数据库的访问速度更快?
What makes access to OLAP Cubes/Datamarts and similar datastructures, faster than to relational databases?
编辑
将尽快提供200的赏金.
A bounty of 200 will be provided asap.
推荐答案
我要说的主要是因为目的不同.
I would say mainly because of different purposes.
OLAP多维数据集/数据集市主要以读取模式用于业务用户的数据分析，而我假设在提到关系数据库时，您所谈论的是OLTP的使用，例如需要ACID事务.
OLAP cubes / datamarts are used mainly in read mode for data analysis by business users whereas I'm assuming when mentioning relational DBs you're talking about OLTP usage requiring for example ACID transactions.
不同目的意味着:
-
实施的不同限制导致不同的数据结构；读/仅数据结构比读/写交易对手快得多；面向行的数据库非常适合OLTP的使用，但是对于OLAP的使用却效率低下(因为无用信息将被无用地访问)，在OLAP中，您主要希望访问整列/度量(因此对垂直DB产生了嗡嗡声；请注意，内存中OLAP系统也是面向列的.
- 对于非常大的系统，OLAP系统还可以对某些维度聚集进行预计算. 不同的内容:不需要完整的运营"数据，并且业务模型可以简化为业务用户的分析目的；那么可以使用数据的子集，可以在创建尺寸等时预先进行连接...
- different constraints for the implementation leading to different data structures; read/only data structures are much faster than read/write counterparties; row-oriented DBs are quite good for OLTP usage but rather innefficient (as useless information is accessed for nothing) for OLAP usage where you mainly want to access a whole column/measure (hence the buzz about vertical DBs; note that in-memory OLAP systems are column oriented as well).
- for very large systems, OLAP systems may perform as well some pre-calculation of certains dimension aggregations.
- different content: the whole "operational" data is not required and the business model might be simplified towards analysis purpose by business users; then subset of data might be used, joins can be done upfront when creating dimensions, etc...
此外，OLAP具有功能更强大的语言(MDX)，具有诸如层次结构维度之类的更高概念；实现可以利用这一点，并提出针对这些概念进行了优化的内部数据结构.
In addition OLAP has a more powerful language (MDX) with higher concepts like hierarchical dimensions; implementations can take advantage of that and propose internal data structures optimized for those concepts.
我的2美分.
这篇关于是什么使对OLAP多维数据集/数据集市和类似数据结构的访问比对关系数据库的访问速度更快?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
