topic Re: Table relationships schema in line in App Development

Table relationships schema in line

HeitorLima — Fri, 08 Oct 2021 13:35:56 GMT

I'm kind of new to this and always see star schemas in table relationship as being good pratice. I always try to achieve that, but I'm facing a situation where my tables relationships are making a straight line, with increasing granularity. Is it bad pratice? Should I try to force a star schema (can't find how yet)?

Example of my schema:

Schools -> Class-> Subjects->SubjectMonthlyHours->Attendance->Enrollments

Attendance is the table with most granularity. In the database, Enrollments are linked with Subjects and Attendance, but in qlik that would make a circular reference.

Thanks in advance

Re: Table relationships schema in line

Andrea_Bertazzo — Fri, 08 Oct 2021 15:33:08 GMT

Hi HeitorLima,

Maybe you can link both Attendance and Enrollments to Subjects.
As you notice, the star schema is generally considered the best. Putting tables in a straight line may decrease the performance and require more CPU when selections are applied. This is not necessarily a big problem if the size of the application is not large and the calculations you are using are to complex.

I hope this article can inspire you.

Re: Table relationships schema in line

HeitorLima — Fri, 08 Oct 2021 17:21:32 GMT

Hi Andrea, thanks for your suggestion. To do that I should make a link table between Subjects and Enrolment and Subjects? Because I can link Attendances directly to Subjects, but I need the link between Subjects e Enrolment.

Thanks for the link, I'm already using some of it's ideas in other projects.