外文翻譯----powerdesigner的起步與數(shù)據(jù)建模-全文預(yù)覽
【正文】 erformance. You may assign types (fact and dimension) to the database tables to have a preview of the multidimensional structure in an OLAP database. ? A multidimensional OLAP database which is generally populated with data that has first been aggregated in a data warehouse or data mart (though sometimes it is transferred directly from operational databases), and in which information is organized to facilitate queries performed by different tools. Business analysts use OLAP databases to send queries and retrieve business information from the different dimensions existing in the database. You use PDM multidimensional diagrams to design the different dimensions and cubes within the OLAP database. a Data Model You can create a new CDM from scratch, by importing a Process Analyst Model (.PAM) or an ERwin model (.ERX), or by generating it from a CDM, PDM, or OOM. You can create a new PDM from scratch, or reverse engineer the model from an existing database. ? To create a new CDM, LDM, or PDM 1. Select File ? New to open the New dialog box. 2. Select one of the following model types: ? Conceptual Data Model ? Logical Data Model ? Physical Data Model 3. Select one of the following radio buttons: ? New model – Creates a new, empty, model. ? New model from template – Creates a model from a model template, which can contain preconfigured options, preferences, extensions, and objects. For more information, see “Model Templates” in the Models chapter of the Core Features Guide . 4. Enter a model name. The code of the model, which is used for script or code generation, is derived from this name according to the model naming conventions. 5. [PDM only] Select a DBMS, and specify whether to: ? Share the DBMS definition – use the original DBMS file in the “Resource Files\DBMS” directory. Changes made to the DBMS are shared by all PDMs that share it. ? Copy the DBMS definition in model – make a copy of the DBMS file. The copied DBMS is saved with the PDM and changes made to it do not impact any other PDMs. 6. [PDM only] Select the type of the first diagram. The diagram chosen bees the default for the next time you cre
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