Logical joins vs Physical joins

Hello,
Can anyone tell me what is the difference between physical joins and logical joins. And how OBI Server treats the joins in relation to the Logical and Physical Layer.
I'm a little confused also with the place to configure the joins, since there is more than one option.
Thanks in advance,
Sofiane

Well actually no. The actual sql fired would depend on both the logical and physical joins. Logical join would be the entry point. Think of it this way. Business Model layer helps you designing a star schema(like a data warehouse) out of your source data. So logical joins are joins that you define on your star schema. But the star schema in itself derives its data from physical layer. So the Physical layer joins would be necessary as well. But if you have a star schema already in your physical layer the physical joins alone would suffice and logical joins are redundant but necessary.
Thanks,
Venkat
http://oraclebizint.wordpress.com

Similar Messages

What is the different between Logical complex join and Physical join?

hi,
Do somebody know what is the function different between logical complex join in BMM layer and physical join in physical layer?
Thanks.

Thank you very much1
I understand their differentiation:
In the BMM Complex join (intelligent), means OBI picks the best way from possibly many different ways to join using physical join. FK join forces the same join always, which limits flexibility.

Diff bw complex join and physical join

hi all
Can sumbody explain me the all the differences between complex join and physical join in the admin tool
Thanks
Shobhit

Hi,
Suggest you to go through this link. It may be helpful in detail.
http://st-urriculum.oracle.com/obe/fmw/bi/biee/r1013/bi_admin/biadmin.html
Thanks,
Vengatesh.

Difference between physical join and logical join

Hi Gurus,
Can anyone tell me what is the difference between physical join and logical join
Thanks,
Chandra

Hi,
A physical join is at the physical layer and defines the join between two physical tables. Logical joins live at the BMM (logical) layer and define a join between two logical tables.
The important differentiation is that at the BMM layer you do not tell the OBIEE server how to do the join, you just tell it that there is a relationship between these two logical entities. When the server comes to this logical join it will use the information in the physical joins and decides how the two logical tables are joined together.
In BMM you use complex joins to establish which logical tables are joined which another, the OBI EE server will go to the physical level to search the physical join to make the query. You can also use physical joins in the BMM to override the join in the physical layer but only in very specific conditions.
If you also set complex join in the physical layer OBI EE won't be able to construct the physical query.
Hope this answers your question.
Award points if helpful.
Thanks,
-Amith.

Error 39008: logical table does not join to fact source

About to lose my mind over this error!
I'm told logical table IT_WORK_ITEM_D (a dimension) does not join to any fact source, although it should show as joined to IT_WORK_ITEM_DSNPSHT_F
- I have verified the physical joins
- I have verified the business model joins
- I have created hierarchies for all logical tables joined to the fact (IT_WORK_ITEM_DSNPSHT_F)
- I have checked the Content tab for the fact table and ensured that the logical dimension is set to the lowset level.
Suggestions from here?
-John

This was helpful, although it did not solve the problem immediately.
After much consistency checking, I cleared out some of the content assignments and that seemed to work (after having not worked). I still don't feel like I identified the core problem, but it is working now.
-John

Between Operator in physical join

Hello,
Can we use between operator in physical join. We did that, its successfully checking in, but when we re-open the join, its show in RED color.
So, got doubt, can we use between?
and we have another error
"No fact table exists at the requested level of detail"; what does this error mean
Waiting for reply...
Regards
Kiran

Can we use between operator in physical join. We did that, its successfully checking in, but when we re-open the join, its show in RED color.
So, got doubt, can we use between?When you checkout the rpd object in online mode it would display in red, this is not an error.
"No fact table exists at the requested level of detail"; what does this error meanThis error usually happens if you have not mapped the content level correctly in the logical table source.
Rgds,
Dpka

Physical Joins Difference Between 10G and 11G?

Hi All, I have started using OBIEE 11G. Anybody please let me know is there any difference in applying physical joins in OBIEE 10G and 11G.
I heard that we need to join Fact and Dim tables in reverse way in 11G.
Thanks in Advance.

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Physical Joins in OBIEE 11G

Hi All,
I just started 11g and am finding it very hard to understand why the physical join is created from Fact to Dimension and how does this qualify as 1:N.
Can anyone explain if I am missing something.
Thanks in advance.

Hi,
A foreign key repository join is used only to define a Primary Key-Foreign Key Relationships in the Physical Layer.
It consist of a column or a set of columns and refers to the primary key column in another table.
When you create it in the physical diagram, you have to point first the dimension and then the fact table.
When you import keys in a physical schema, the primary key-foreign key joins are automatically defined.
If you want to define other relationship, you have to use a complex join.
And,
In the business model, OBI recommends using complex logical joins instead of foreign key logical joins.
When Complex joins are used in the business layer then they are really acting as placeholders. They allow the OBI Server to decide on which are the best joins define in the Physical Layer to satisfy the request.
In a Dimension, you may have multiple Logical Table sources that all join to one fact table. The OBI Server will then decide the best joins to use to meet the requirements.
Regards,
MuRam

Outer Joins in physical layer

Hello BI people - I'm new in this issue and I need help.
I'd like to do sth like outer join in physical layer between two tables and I can't :(
For example
Table CUSTOMERS and table REGIONS for customers. Table CUSTOMERS has colum: POSTAL_CODE and in table REGIONS I have primary key:POSTAL_CODES. till now everything looks simply PK to FK 1:n relation but sometimes happens that in table customers there are nulls or mistakes in this field (reason: bad written application, dirty data etc)
and when I don't use OUTER JOIN I'll lose some records about customers - I would like to see that records even with cleared region informations. How to do it in BI -use VIEWS ? Can I join two physical tables with outer join?
Thanks for help

Ok. You have to resolve this in the logical layer as wel.
When you click on custumers and then on sources.
What do you see there?
Do you only see one source or 2 sources?
If you see 2 sources, then just delete one and double click on the source that is left over. In here you can join with the other table and choose outer join.
Good luck ;)

Unable to do Physical Join in rpd

Hi
I tried to join table Ra_Customer_trx_all and OE_order_header_all but the join condition is to_char(OE_order_header_all .order_number) = Ra_Customer_trx_all .Attribute6
can i use this join condition in physical layer..Because in physical join we staraightway give the join condition but here we are changing the column type and then using the join.
I am using OBIEE 11g
thanks in advance for the help
Debo

Hi
Thanks for the solution in physical join but when i simply join the two tables in the business layer the logical join is not pulling any data..Do we need to do something else to do the logical join between those tables
Regards
Debo

Use of complex join in BMM and Physical Join in Physical layer ?

Hi All ,
Why we need to use complex join in BMM layer not the Physical Join ?
Why we need to use Physical Join in Physical layer not Complex join ?
thanks in advance

Hi,
A physical join is at the physical layer and defines the join between two physical tables.
Logical joins live at the BMM (logical) layer and define a join between two logical tables.
The important differentiation is that at the BMM layer you do not tell the OBIEE server how to do the join,
you just tell it that there is a relationship between these two logical entities.
when the server comes to this logical join it will use the information in the physical joins and decides how the two logical tables are joined together.
thanks,
pramod.

Can we create a multiple joins in physical layer

Hi,
I have a requirement that i want to create a multiple joins in physical layer.
Ex:
Table a (custid,name,sal) and tableb (custid,ced_id, loc)
i had requirement that cust id is joining with custid and cedid from table b
i.e a.custid=b.custid AND
a.custid=b.ced_id (Note data types are same across all the joins here).
When am trying to handle it form physical joins, getting an issue that The column'cusid' is used twice.
Regards,
Malli

As Daan said use complex join in physical layer that should work. Just in case its not working then go with 1 join condition physical layer and create foreign key join in BMM layer, this would override join in physical layer.

Join in Physical Layer

hi all,
is it possible to give right outer join in physical layer? if so how can we do that? actually Type options is not visible in physical diagram.
thanks

No, outer joins are created in the bmm layer.

How can we achieve the outer join in physical layer

Hi,
Can any one can suggest ,how do we handle the outerjoin criteria in obiee.
thanks
B.kumar

Its not advisable as such to use complex join in physical layer......Use physical primary-foreign key relationship join on the tables.
But looking at your where condition
where tab1.date between tab2.start_date and tab2.end_dateIt is not possible because you are taking table1 date and giving the table 2 dates for evaluation.
it should be this way if its primary key relation ship.
where tab1.date between tab1.start_date and tab1.end_dateIf it is equi-join then you need to write what you have mentioned in your query.
Cheers,
KK

Fact joins in Physical ayer

Hello All,
I recently joined in a project, I was going through the RPD and I can see there are Fact to Fact joins in Physical layer..however there are no Fact joins in BMM layer.
I'm trying to understand why these joins are created and how it will impact in BI query's. Thanks...

It is Fact to Fact Extension they have joined i guess.
http://satyaobieesolutions.blogspot.com/2012/07/implementing-multiple-fact-tables-in.html
Mark if helps.

Logical joins vs Physical joins

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