About Heli

Kirja Twitter: @Helifromfinland
I am
– the author of Oracle SQL Developer Data Modeler for Database Design Mastery (McGraw-Hill, Oracle Press, 2015)
– a co-author of Real World SQL and PL/SQL: Advice from the Experts (McGraw-Hill, Oracle Press, 2016)
– one of the first winners of Oracle Database Developer Choice Award, Devvy, on Database Design category in 2015
– a frequent speaker in many conferences
I am
– the CEO for Miracle Finland Oy
– an Oracle ACE Director
– a PhD student and a researcher at the University of Helsinki. My research is related to Big Data.
I have been an Oracle user since 1993. 
I love cooking, reading, writing, and sports.
In short: I am a database person and I come from Finland.

Oracle SQL Developer Data Modeler for Database Design Mastery

http://www.mhprofessional.com/product.php?isbn=0071850090

http://www.amazon.com/Oracle-Developer-Modeler-Database-Mastery/dp/0071850090

 

Real World SQL and PL/SQL: Advice from the Experts

http://www.amazon.com/Real-World-SQL-PL-Experts/dp/1259640973/

 

 

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6 thoughts on “About Heli”

  1. Heli, I’m looking for some advice. We have about 8 existing star schemas in our database and most of them are using conformed dimensions. Haven’t used DataModeler to create them. I’d like to reverse engineer all of them into DataModeler and then start on a new star schema design that is needed. Should I reverse engineer them all into one single relational model or what? Or do I create different/separate datamodeler files for each star schema? There are 4-5 schemas involved already. I don’t know how to approach this. By the way, we bought your Oracle SQL Developer Data Modeler book. Thanks, John from State Univ. of New York.

    • Hi John!
      Usually when schemas have someting in common (foreign keys between the tables in different schemas, shared tables etc) I bring them into a single design and create a subview for each schema. If they have nothing in common I create several designs. Sometimes the problem with a single design can be that due to so many tables it can be too slow to work with. The latest release is better in that way and should have less issues.
      Does this help?
      Cheers,
      Heli

  2. Thank you for your advice Heli! I will try your idea. I’ll import everything into one relational design and then separate them out into subviews, one for each “star”. I guess the only issue might be if another person wants to do work on one of them at the same time then we only have one file.

    • Hi John
      not a problem at all: each element will be in a separate file (entity, table, diagram etc) and several people can work on them at the same time. The whole design is in one file only if you specifically tell the tool you want to have everything in one file (Design Properties, makes handling larger designs faster). Still if you use Subversion and DO NOT use locking you can use it in a multiuser environment. Several people can work on it at the same time and if conflicts arise you are able to solve them.
      If you are not using Subversion yet, please consider that seriously: when everything is in version control you do not need to worry about making mistakes, you can always go back to the point before the mistake was made 🙂
      Cheers
      Heli

  3. Heli, is there a technique in logical design to show the role playing dimensions as separate entities? right now we just see one entity with multiple relationship lines to the fact table. not very user understandable. Thanks again!

    • Hi John. I am not sure what would be the best but I suggest you add the role name as the Name on Source (for instance OrderDate, DeliveryDate) at the relationship properties (double click the relationship and edit Name on Source property). In the relational model you might want to use views for the different roles? Defining attributes (OrderDate, DeliveryDate,…) for each relationship is another way of thinking. There are several ways of doing it but I am not sure which one is the best. Have you used another tool before? If so how did you do it with that?

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