Dimensional Object的ROLAP Implementation和MOLAP Implementation的区别以及Deployment Option的说明
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ROLAP Implementation of Dimensional Objects
首先,对名称ROLAP Implementation里的ROLAP部分解释下:
ROLAP=relational+OLAP。因为ROLAP Implementation(实施)针对的对象是维和方体,而维和方体这两种对象虽然存储在数据库中,但是一般我们使用的工具,如sql*plus只能使用维和方体这两种对象对应实施的关系表(a relational database table)的形式,如果这两种对象以ROLAP Implementation方式实施的话,而在OLAP软件(工具)中,维和方体这两种对象则可以自身的逻辑结构展现出来,故而维和方体这两种对象算是为OLAP软件(工具)特别设计使用的对象,所以将维和方体这两种对象的实施方法称为OLAP Implementation。又由于该实施方法是将维和方体这两种对象对应实施到一个关系表(a relational database table)上,所以称该实施方法为ROLAP Implementation。
注释:
1、这里提到的OLAP指的是OLAP工具,不是在dbca界面上看到的数据库类型里的数据库仓库类型(还有一般或事务处理类型)。
OLAP (systems)
Short for OnlineAnalytical Processing, a category of software tools that provides analysis of data stored in a database.
OLAP tools enable users to analyze different dimensions of multidimensional data. For example, it provides time series and trend analysis views. OLAP often is used indata mining.
The chief component of OLAP is the OLAP server, which sits between a client and a database management systems (DBMS). The OLAP server understands how data is organized in the database and has special functions for analyzing the data. There are OLAP servers available for nearly all the major database systems.
参考:
谷歌 OLAP
http://www.webopedia.com/TERM/O/OLAP.html
http://en.wikipedia.org/wiki/Online_analytical_processing
2、oracle数据库软件的核心就是组成数据库的那些操作系统上的(物理)文件(如,数据文件、控制文件、日志文件)以及用于操作管理数据库的rdbms(即关系数据库管理系统:组成关系数据库管理系统的各个进程构成了操作管理数据库的环境,而一个实例里的后台进程可以说是组成关系数据库管理系统的各个进程中的一部分,也可以认为是运行于由组成关系数据库管理系统的各个进程构成的环境的上一层,即一个实例里的后台进程的成功运行依赖于这个环境),而像sql*plus、sql Developer、OLAP等工具(都是oracle数据库软件的组件)则是运行于由组成关系数据库管理系统的各个进程构成的环境的上一层,即这些组件的成功运行依赖于这个环境。当然,rdbms,即关系数据库管理系统,随着版本的升级,其功能得到不断的扩展,如oracle11g中加入的闪回这个新特性等。再分类的话,sql*plus、sql Developer是客户端工具,OLAP工具是服务端工具。
A ROLAP implementation, like(如) a relational implementation, stores the dimensional object and its data in a relational form in the database. Additionally, depending on the type of ROLAP implementation, it either creates CWM2 metadata in the OLAP catalog or OLAP cube materialized views.
This section describes how ROLAP implementations are classified
(ROLAP implementation分为两类,一个是 ROLAP Implementation :关系存储,一个是ROLAP with MVs Implementation):
1、ROLAP Implementation (在设计中心界面上,称为 ROLAP Implementation:a relational implementation,或ROLAP Implementation:关系存储)
The dimensional object and its data are stored in a relational form(关系型格式,如表的存储结构) in the database ,
and the CWM2 metadata for the dimensional object is stored in theOLAP catalog.This enables you to query the dimensional object from Discoverer (for OLAP).
2、ROLAP with MVs Implementation (ROLAP with cube MVsImplementation,其中,MVs= materialized views)
The dimensional object and its data are stored in a relational form in the database(andthe CWM2 metadata for the dimensional object is stored in theOLAP catalog???). Additionally,cube-organized materialized views are created in ananalytic workspace.
Note:
In Oracle Warehouse Builder 11g Release 2 (11.2), only star schema tables are supported for the ROLAP with MVs implementation.About OLAP Catalog
The OLAP catalog is the metadata repository provided for the OLAP option in the Oracle Database.
This metadata describes the data stored in relational tables(例如,the CWM2 metadata for the dimensional object is stored in theOLAP catalog,describes the dimensional object 's data that stored in a relational form(关系型格式,如表的存储结构) in the database).
When you deploy a dimensional object using Warehouse Builder, you can specify if the dimensional object metadata should be stored in the OLAP catalog.
OLAP metadata(the CWM2 metadata是OLAP metadata中的一种,还是就是OLAP metadata) is dynamically projected() through a series of views called the active catalog views (views whose names begin with ALL_CWM2_AW).
In Oracle Database 10g, the OLAP catalog metadata is used by OLAP tools and applications to access data stored in relational star and snowflake schemas. External application such as Discoverer use the OLAP catalog to query relational and multidimensional data. The application does not need to be aware of whether the data is located in relational tables or in analytic workspaces, nor does it need to know the mechanism for accessing it.
The OLAP catalog uses the metadata it stores to access data stored in relational tables or views. The OLAP catalog defines logical multidimensional objects and maps them to the physical data sources. The logical objects are dimensions and cubes. The physical data sources are columns of a relational table or view.
MOLAP Implementation of Dimensional Objects
In a MOLAP implementation, the dimensional object data is stored in ananalytic workspace in Oracle Database 10g or Oracle Database 11g.
(The dimensional object is stored in a relational form(关系型格式,如表的存储结构) in the database andthe CWM2 metadata for the dimensional object is stored in theOLAP catalog???)
This analytic workspace, in turn, is stored in the database.
If the Oracle location of the computer containing the AW uses Oracle Database 10g, then the OLAP 10g form analytic workspaces are generated. If the location used Oracle Database 11g, then the OLAP 11g form analytic workspaces are generated.
Analytic Workspace
An analytic workspace is a container within the Oracle Database that stores data in a multidimensional format(格式). Analytic workspaces provide thebest supporttoOLAP processing.An analytic workspace can contain a variety of objects such as dimensions and variables.
An analytic workspace is stored in a relational database table, which can be partitioned across multiple disk drives like any other table. You can create many analytic workspaces within a single schema to share among users. An analytic workspace is owned by a particular user and other users can be granted access to it. The name of a dimensional object must be unique within the owner's schema. For more information about analytic workspaces, seeOracle OLAP User's Guide.
注释:
Dimensional Object的ROLAP实施和MOLAP实施的区别,在于
ROLAP Implementation of Dimensional Objects
The dimensional object andits dataare stored in arelational form(关系型格式,如表的存储结构) in the databaseMOLAP Implementation of Dimensional Objects
the dimensional object data is stored in ananalytic workspace in Oracle Database 10g or Oracle Database 11g.
An analytic workspace is a container within the Oracle Database that stores data in a multidimensional format(格式).
也就是说,两者存储The dimensional object data的格式以及位置不同。
Deployment Options for Dimensional Objects
After you define dimensional objects, you must deploy them toinstantiate(实例化)[即deploy等于实例化的意思] them in the database. To specify the type of implementation for dimensional objects, you set the configuration parameter Deployment Option.
Warehouse Builder provides the following deployment options for dimensions: Deploy All, Deploy Data Objects Only, Deploy to Catalog, and Deploy Aggregation.
Deploy All For a relational or ROLAP implementation, the dimension is deployed to the database anda CWM definition to the OLAP catalog.
Deploy All
For a ROLAP with MVs implementation, the dimension is deployed to the database and cube-organized materialized views are created in an analytic workspace.
Deploy All
For a MOLAP implementation, the dimension is deployed to the analytic workspace.
Deploy Data Objects Only Deploys the dimension only to the database.
You can select this option onlyfor dimensions that use a relational or a ROLAP implementation.
Deploy to Catalog Deploys the CWM definition to the OLAP catalog only.
Use this option if you want applications such as Discoverer for OLAPto access the dimension data after you deploy data only.
You can also use this option if you previously deployed with "Data Objects Only" and now want to deploy the CWM Catalog definitions without redeploying the data objects again.
Deploy Aggregation Deploys the aggregations defined on the cube measures. This option is availableonly for cubes.
来自:http://docs.oracle.com/cd/E18283_01/owb.112/e10935/dim_objects.htm#BABJBCAA
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