Universe Schema

[former_member213259]

Hello Experts,

I am building an Universe and running into the below issue. Please advise ways to handle it.

I have three tables, table 1, table 2 and table 3 whose structure is as below.

Table 1         

Col_1_1

Col_1_2

Table 2

Col_2_1

Col_2_2

Col_2_3

Col_2_4

Table 3

Col_3_1

Col_3_2

Col_3_3

Col_3_4

Col_3_5

The relationship among these three tables are:

Table2.Col_2_2 = Table1.Col_1_1

Table2.Col_2_3 = Table1.Col_1_2

Table3.Col_2_2 = Table1.Col_1_1

Table3.Col_2_3 = Table1.Col_1_2

When Table 1 and Table 2 are joined in the schema with the above given relationship, things look good. However, when I try to joinTable 3 and Table 1,I get incompatible combination of tables error. This gets resolved by creating an alias of Table 1 and joining it to Table 3. I want to avoid the alias tables as there are many such relationships. Please advise on the same.

Thanks!

[Former Member]

Hi,

I am afraid that the information you have provided is too generic and does not provide enough context of the business process that you're working with.

In a dimensional model,

- we generally use aliases for dimensions which are used as a reference in the fact table more than once.

- we use contexts when there are multiple fact tables

Both the above are done to avoid loops. You can search about loops and traps in universe design and need to understand them well before getting into universe design. I also recommend that one must have good understanding of the underlying data objects (tables/vews) and relationships.

Cheers

Mohan