URGENT MODELING SNOW FLAKE SCHEMA

Hi i have 2 fact tables fact1 and fact 2 and four dimension tables D1,D2,D3 ,D4 & D1.1 ,D1.2 the relations in the data model is like this :
NOTE: D1.1 and D1.2 are derived from D1
[( D1.. 1:M..> Fact 1 , D1.. 1:M..> Fact 2 ), (D2.. 1:M..> Fact 1 , D2.. 1:M..> Fact 2 ), ( D3.. 1: M.> Fact 1 , D3.. 1:M..> Fact 2 ),( D4.. 1:M..> Fact 1 , D4 ... 1:M..> Fact 2 )]
Now from D1 there is a child level like this: [D1 --(1:M)..> D1.1 and from D1.1.. 1:M..> D1.2.. 1:M..> D4]
Please help me how to design in physical layer and BMM layer. I will be very glad to you guys this is very urgent requirement.
PS: Deepak Gupta you are very helpful earlier please help me.
Thanks,
ch

They too are snowflake.... but we speak snowflake w.r.t dimension attached to FACT...
Alternate solution, but of the same type..
First of all create aliases for all the Tables in physical layer... but create two aliases for D1 , say D1.A1 & D1.A2
Note: you need to create joins between aliases only, no need of creating joins between original tables ..
In Physical Layer, just have all the joins as Physical Foreign Key Join, just the way you have described, making sure that
D1.A1 is connected only to both the facts aliases...
and
D1.A2 is connected only to D1.1 alias
Drag all the aliases in BMM
Now work with Aliases only in BMM Layer
Here D4 is snowflaked...
So in BMM just bring D4 Alias from Physical Layer and onto it, drop D1.1 alias, D1.2 alias and D1.A2 alias , so that now you have 4 logical table sources under 'Logical Table folder' D4.
This is it....
The Only thing is that you ll have to create two Aliases for D1...
Thanks
Ashish Gupta

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Hi Experts,
Can any one post few scenarios regarding Implementation of snow flake schema which can not be converted to star schema in BMM layer for better under standing about schemas. I searched my blogs but i did not found exact answer.
Regards,
Rafi

Rafi,
Check these links
http://iniu.net/content/obiee-define-star-schema-over-snowflake-data-model-data-source
http://www.varanasisaichand.com/2012/05/denormalizing-physical-tables-in-bmm.html
http://majendi.blogspot.com/2009/01/obiee-snowflakes-and-stars-part-3.html
http://blogs.datadirect.com/2012/02/obiee-oracle-business-intelligence-integration-with-salesforce-com-crm-and-database-com-via-odbc.html
In general if you follow the OBI best practices you never get snowflake schema in BMM layer.
If helps pls mark

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can any one tell star schema is better or snow flake schema is better why
thx in advance

Hi,
Difference : http://www.diffen.com/difference/Snowflake_Schema_vs_Star_Schema
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HR schema which is more like a snow-flake schema structure
Refer http://www.varanasisaichand.com/2012/05/denormalizing-physical-tables-in-bmm.html
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anybody give me some knowledge about snow flake schema.
in which type of situations,useually snow flake schema creates in data model.
can you please provide me with example?
Thanks in Advance.

In case of large dimesnsion, we will split them to smaller dimensions, this is to make the table better manageable.
Let's take an example you have a Dimension table which stores the information about the shop details, you may have a seperate dimension table which hold the dempgraphic information of the sales area this provide the logical separation of data.
You have to decide based on your data and requirement whether to go for snowflake or Star.
If you have snowflake defined, will be flattened the same in the logical layer of OBIEE.
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Vino

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Dear Reader,
I facing a problem like that
I have two data warehouse, one use star schema, other use snow flake schema. I would like to integrate both of them into one data warehouse. What is the strategy should these two data warehouse adopt in order to integrate int one data warehouse?
Should I scrap both data warehouse and build a new one instead, or scrap one of them and use the other?
What factors should be considered in order for me to more easily resolve the differences between the two data warehouses.
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Hi Mallis,
This is a very broad question and the answer depends on so many factors. Please go through the following articles to get an
understanding of what the differences are when to use which.
When do you use a star schema and when to use a snowflake schema -
http://www.information-management.com/news/10000243-1.html
Star vs Snowflake Schemas – what’s your belief? –
http://www.networkworld.com/community/blog/star-vs-snowflake-schemas-%E2%80%93-what%E2%80%99s-your-belie
Hope this helps!

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Hi,
I would like to know following things
1. Can we use more than one star or snow flake schema for an universe? and how to do this?
2. Using multiple shemas for one universe is it good practice or not?
Regards,
Manjunath

Manjunath,
This is exactly where BusinessObjects excels.
When dealing with multiple fact tables, you use contexts.
Contexts are very simple to understand and you must take your time to do so if you are going to successfully develop universes based on more than one fact table. No matter what universe you build, the rule for contexts is always the same; there are no different circumstances based on, say, industry.
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For example, consider the very basic schema below:
D1 -< D2 -< F1 >- D3 -< F2 >- D4
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As for one-to-one joins, set the cardinality as one-to-many in the direction that you know the relationship should be in for the ownership to work out correctly..
The process that I've described above is essentially how the Detect Contexts algorithm works.
The only remaining thing for you to read up on is the SQL parameters but essentially you need ot be able to select multiple contexts and generate multiple sql statements for each context. Otherwise, what's the point in defining them?!!
Hope that clears it up for you.
Regards,
Mark

Snow flake schema to star schema

Hi Gurus,
I am having a snow flake schema how can i turn it into star schema.
thanks,
kumar

In Obiee You can use multiple table source and join 2 tables abd make as singel table.
EX A->B->C
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IN the column mapping you can mpa the column to desired physical table.
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Get A and B into presentaion layer.
mak if correct/helpful
fiaz

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i have snow flake data model.
anybody tell me how can i convert that snow flake to star by doing the adding multiple sources to a dimention.
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Hi
we can do that for example we have dimension table that connected with another dimension table in physical layer
solution- create one new dimension table in bmm layer and drag the columns from two dimension table which in physical layer and give the join condition it ll work,...
Regards
prabhu haridass

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Hello
whats the procedure to resolve the problem if we are able to only build a snowflake schema
my tables are like this:
fact table: sales
dimesion tables: customers, products, orders
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so it is forming a snow flake in physical layer and how to we do make in BMM to form a star schema
if we are dragging columns from countries to customers in BMM, will that work effiecently as expected because as a user i am not able to see the data from both the tables. i am working on SH schema from ORACLE 10g database
thanks
rake

rake,
I suggest you do some reading on dimensional modeling and use aliases and multi-source LTSs
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Hello,
I believe this is a bug report.
Scenario:
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Hi Kurt,
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Using DM 3.3.0.747.
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Philip

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Hi All,
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Hi Philip,
You are righ, if a select this option in the compare tab options
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URGENT MODELING SNOW FLAKE SCHEMA

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