HANA Architecture

1　　HANA 是基于内存计算的。行列都支持。使用列存储，列存储的特点是高压缩，查询快，节约空间， ---SAP HANA supports both, but is particularly optimized for column-order storage.。

　　 SAP HANA employs highly efficient compression methods, such as run-length encoding, cluster coding and dictionary coding 。 压缩方法

　　列存储 一般情况下需要添加索引结构--Columnar storage, in many cases, eliminates the need for additional index structures

　    消除索引带来的后果。Eliminating additional indexes reduces complexity and eliminates the effort of defining and maintaining metadata.

　　列存储的缺点，添加修改会比较麻烦。

　　

2  并行处理。

　SAP HANA 设计是执行基本的计算--SAP HANA was designed to perform its basic calculations 。

　它能同时利用几百个core计算。 it uses hundreds of cores at the same time, fully utilizing the available computing resources of distributed systems.

　Compressed data can be loaded into the CPU cache faster. This is because the limiting factor is the data transport between memory and CPU cache, and so the performance gain exceeds the additional computing time needed for decompression.   内存和CPU之间。它直接放内存里自然快。就是花钱。内存贵。硬件性能。

　　

3 虚拟聚合

　Traditional business applications often use materialized aggregates to increase performance。都是实例化聚合来提高性能。HANA建的都是虚拟视图。

　SAP HANA makes it possible to calculate aggregates on large amounts of data on-the-fly with high performance. This eliminates the need for materialized aggregates in many cases, simplifying data models, and correspondingly the application logic  优点。

　Furthermore, with on-the fly aggregation, the aggregate values are always up-to-date unlike materialized aggregates that may be updated only at scheduled times.。缺点

　　总是需要更新，不想实例化的只用在计划时间更新就好。