SQL Server Performance

Top 10 Must Have Features in O/R Mapping Tools

Discussion in 'Performance-Related Article Discussions' started by shanetasker, Jan 12, 2006.

  1. shanetasker New Member

  2. satya Moderator

    Good article to help in such areas.
    I never worked on such tools so far, as there wasn't any such requirement at my end.
    But I believe SQL 2005 has more features in this regard.

    Satya SKJ
    Contributing Editor & Forums Moderator
    http://www.SQL-Server-Performance.Com
    This posting is provided “AS IS” with no rights for the sake of knowledge sharing.
  3. FrankChicharelli New Member

    I thought this web site was called Sql-Server-PERFORMANCE.com? Emphasis on Performance. What is this article doing here? Is O/R mapping something that should be used in order to improve performance?





  4. FrankKalis Moderator

    Don't be too hard here. It certainly doesn't hurt to look over the rim of our coffee cup, does it? [<img src='/community/emoticons/emotion-1.gif' alt=':)' />]<br /><br />--<br />Frank Kalis<br />Microsoft SQL Server MVP<br /<a target="_blank" href=http://www.insidesql.de>http://www.insidesql.de</a><br />Heute schon gebloggt?<a target="_blank" href=http://www.insidesql.de/blogs>http://www.insidesql.de/blogs</a><br />
  5. mmarovic Active Member

    Yes, good mapping helps avoid performance problems. [<img src='/community/emoticons/emotion-1.gif' alt=':)' />] Prevention rules!
  6. satya Moderator

    Object/relational mappings are usually defined in an XML document. The mapping document is designed to be readable and hand-editable. It is useful when XML and any other relational objects are used in SQL Server. Basic topic behind that concept is "An object with multiple dependencies and relationships with other objects may trigger a raft of SELECTs when instantiated."

    Satya SKJ
    Contributing Editor & Forums Moderator
    http://www.SQL-Server-Performance.Com
    This posting is provided “AS IS” with no rights for the sake of knowledge sharing.
  7. FrankKalis Moderator

    Now, isn't it really nice to have this feature to discuss published articles. [<img src='/community/emoticons/emotion-2.gif' alt=':D' />]<br /><br />--<br />Frank Kalis<br />Microsoft SQL Server MVP<br /<a target="_blank" href=http://www.insidesql.de>http://www.insidesql.de</a><br />Heute schon gebloggt?<a target="_blank" href=http://www.insidesql.de/blogs>http://www.insidesql.de/blogs</a><br />
  8. mmarovic Active Member

    quote:One table for all objects: In this pattern, the base object and all the derived objects are represented in one table in the database. This table contains columns representing attributes from all the objects. It is most efficient for loading and saving data but is very limited because adding a new object to the inheritance requires changing the structure of an existing table in the database, which is highly undesirable.

    Keeping this in mind, the O/R mapping tool must support at least the "One table per object" approach and if it can also support this second approach that is icing on the cake.
    The article gave me information about existence of tools I didn't know.
    However, I don't agree with the bold part. If I got explanation right, one table for all objects = totally ingnoring normalization. If so, this is not the most efficient structure for loading and saving data by any mean. Because of that, support for such approach is not the icing on the cake, it is support for a terrible practice.
  9. Adriaan New Member

    One sometimes gets requests like "can't we have a more flexible structure for our main object table" - as in: add a subtable for "optional columns". Sure, no problem in creating that, but then try to implement some business logic and business rules on top of it.

    One table for all objects is the other end of the spectrum, where you have a number of shared columns between objects, but also rather a lot of columns that must be entered for one type of objects, but not for the others, etc. etc. Same problems with business logic & rules.

    If you need to implement business logic & rules, then make sure object definitions are clean and clear. No room for compromise.

    Also understand that other systems do not necessarily have the same level of detail as your system.
  10. bradmcgehee New Member

    While the focus of the website is on peformance (and clustering to a degree) we welcome SQL Server articles of all types. I know I still have a lot to learn.

    -----------------------------
    Brad M. McGehee, MVP
    Webmaster
    SQL-Server-Performance.Com

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