Results 1 to 8 of 8
  1. #1
    Join Date
    Jul 2010
    Posts
    8

    erd that reflects data warehouse design

    hi!! ^^

    I would like to know if there's a difference between a normal erd and an erd that reflects data warehouse design.

    Thanks

    Regards,
    shinichi90

  2. #2
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    no, there is not

    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  3. #3
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    The ERD for the relational part(s) of a Data Warehouse is like any other relational database, but the design issues are quite different. The ERD for the client-facing portion or surface of a Data Warehouse (often a cube instead of a database) is often radically different from a relational ERD. The degree of difference between those ERDs is usually tied to which of the Datawarehouse methodologies you use, and there can be more than one presentation for the same source data (for example the SAP Analysis Tools, Microsoft's SSAS, Cognos, and EssBase), and sometimes the relational portion that feeds each of them can be different (although this is probably the DBAs worst-case scenario).

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

  4. #4
    Join Date
    Jul 2010
    Posts
    8
    Quote Originally Posted by Pat Phelan View Post
    The ERD for the relational part(s) of a Data Warehouse is like any other relational database, but the design issues are quite different. The ERD for the client-facing portion or surface of a Data Warehouse (often a cube instead of a database) is often radically different from a relational ERD. The degree of difference between those ERDs is usually tied to which of the Datawarehouse methodologies you use, and there can be more than one presentation for the same source data (for example the SAP Analysis Tools, Microsoft's SSAS, Cognos, and EssBase), and sometimes the relational portion that feeds each of them can be different (although this is probably the DBAs worst-case scenario).

    -PatP
    ooo....I'm not really sure if i understand all of this clearly...>< I have learned basic database and only recently started to learn more about data warehouse..

    so, if I were to draw out the erd would this two erd be different or the same?

  5. #5
    Join Date
    Apr 2002
    Location
    Toronto, Canada
    Posts
    20,002
    Quote Originally Posted by Pat Phelan View Post
    The ERD for the relational part(s) of a Data Warehouse is like any other relational database...
    thanks for confirming my reply

    shinichi90, pat is right, the design issues are quite different, but in the end all ERDs are the same in that they use the same diagramming techniques (boxes with lines connecting them, and maybe arrows or crowsfeet or little golden mario keys on the end of the lines, but all the diagrams in your company would have the same conventions)

    i think i know what you're asking, though, but before you get too worried about it, ask yourself what you mean by a "normal" database
    rudy.ca | @rudydotca
    Buy my SitePoint book: Simply SQL

  6. #6
    Join Date
    Feb 2004
    Location
    In front of the computer
    Posts
    15,579
    The ERD diagrams for the Staging and the Atomic levels within the DataWarehouse would be the same as any other relational database. As you move beyond the Atomic level, odds are good that the ERD would change in both concepts and presentation. The ways in which it would change would depend on which ERD notation you use which is usually closely tied to the methodology and the underlying Business Intelligence tools that you choose.

    -PatP
    In theory, theory and practice are identical. In practice, theory and practice are unrelated.

  7. #7
    Join Date
    Jun 2003
    Location
    Ohio
    Posts
    12,592
    Your database should have a logical ERD, representing the various entities and attributes to be tracked, and a physical ERD representing the way those entities and attributes are stored in tables and columns.
    For simple databases, the Logical and Physical ERDs are virtually identical. For more complex database designs, and for data warehouses, they are usually different.
    If it's not practically useful, then it's practically useless.

    blindman
    www.chess.com: "sqlblindman"
    www.LobsterShot.blogspot.com

  8. #8
    Join Date
    Jul 2010
    Posts
    8
    I think I understand some a bit....Thank you all for the quick replies ^_^
    I'll try to do some more research on my own.

    Regards,
    shinichi90

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •