etl olap

得到ETL的定义：
    将数据抽取（Extract）、转换（Transform）、清洗（Cleansing）、装载（Load）
MDX是一种和SQL类似的语言，它也可以用于查询、计算和定义一些元数据。只不过SQL是基于OLTP的，而MDX是基于OLAP的，也就是说，MDX是对多维数据进行查询的。和其它的OLAP语言不同，MDX并不完全是一种报告形式语言。但用MDX查询出来的结果仍然可以在客户端程序中以表格形式进行展现。MDX和SQL一样，也有很多不同功能的API来支持MDX。


OLAP dashboard
An OLAP dashboard, also referred to as a business intelligence, or BI dashboard, is a visual display with two or more reports and/or graphs on a single computer screen. OLAP dashboards are used by all levels of management to get an overall picture of various aspects of the business in a single, concise format.  The data that is visualized in the dashboard may or may not come from the same data source.  


The OLAP designation indicates that one or more of the graphs or reports (sometimes referred to as “panes,” in the dashboard) are based on an Online Analytical Processing (OLAP) data source.  OLAP data sources are multi-dimensional, in that they allow for reporting on several different variables (also known as dimensions), sometimes at the same time, with the flexibility to select only a subset of the variables at a time.


Many of the graphs or reports in the OLAP dashboard allow for “drilling” up or down, which refers to the ability to add or remove variables in the report, or see transaction or account detail records for the particular cell in the report (or bar/point/area on the graph).  Dashboards commonly include anything from basic tabular reports, pie charts, bar charts, line graphs, to more complicated reports with traffic lighting and automatic threshold e-mail alerts, maps, gauges, pyramids, spark charts and scatter plots with trend lines. The options for reports and graphs available in an OLAP dashboard may be limited by the vendor. 


OLAP dashboards require considerable setup on the back end, but once they are developed and employees have been trained how to use them, they become indispensable tools for helping a company's employees to make informed decisions based on data.