Using two facts of two different star schemas and conformed dimensions

Hi,
I've been working as developer and database designer for years and I'm new to Business Objects. Some people says you can not use two facts of two different star schemas in the same query because of conformed dimensions and loop problems in BO.
For example I have a CUSTOMER_SALE_fACT table containing customer_id and date_id as FK, and some other business metrics about sales. And there is another fact table CUSTOMER_CAMPAIGN_FACT which also contains customer_id and date_id as FK, and some other business metrics about customer campaigns. SO I have two stars like below:
DIM_TIME -- SALE_FACT -- DIM_CUSTOMER
DIM_TIME -- CAMPAIGN_FACT -- DIM_CUSTOMER
Business metrics are loaded into fact tables and facts can be used together along conformed dimensions . This is one of the fundamentals of the dimensional modeling. Is it really impossible to use SALE_FACT and CAMPAIGN_FACT together? If the answer is No, what is the solution?
Saying "you cannot do that because of loops" is very interesting.
Thank you..

When you join two facts together with a common dimension you have created what is called a "chasm trap" which leads to invalid results because of the way SQL is processed. The query rows are first retrieved and then aggregated. Since sales fact and campaign fact have no direct relationship, the rows coming from either side can end up as a product join.
Suppose a customer has 3 sales fact rows and 2 campaign fact rows. The result set will have six rows before any aggregation is performed. That would mean that sales measures are doubled and campaign measures are tripled.
You can report on them together, using multiple SQL passes, but you can't query them together. Does that distinction make sense?

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Joining two fact tables with different dimensions into single logical table

Hi Gurus,
I try to accomplish in Oracle Business Intelligence 11.1.1.3.0:
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F2 (D1 and D2 and D4)
And we want to build a report F1 F2 D1 D2 D3 D4 to have data for:
F1 that match only for D1-D2-D3
and data for
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Here is the very good example how to accomplish the scenario 1
http://108obiee.blogspot.com/2009/08/joining-two-fact-tables-with-different.html
But looks like it does not work in 11.1.1.3.0
I get
State: HY000. Code: 10058. [NQODBC] [SQL_STATE: HY000] [nQSError: 10058] A general error has occurred. [nQSError: 43113] Message returned from OBIS. [nQSError: 14025] No fact table exists at the requested level of detail: [,,Clients,,Day,ROI,,,,EW_Names,,,,,,,,,,,,,,,,,]. (HY000)
I am sure I set up everything correctly as advised in the blog but it works with only one not a common dimension
Is it a bug in 11.1.1.3.0 or something?
Thanks,
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Thanks for all your replies.
Actually, I've tried the solutions you guys mentioned. Generally speaking, the result should be displayed. However, my scenario is a little bit tricky.
table Y's figures are not the aggregation of table X for D dimension. Instead, table Y's figures include not only D dimension total, but also others (others do not mean A, B, C dimension). For example, table Y stores all food's figure, while table X stores only drink's figure. D dimension is only about drink's detail. In my scenario, other foods' figure is not provided.
So, even if I set D dimension to all/total for table X, table X's result is still not the same as table Y.
Indeed, table Y does not have a column key to join to D dimension's key. So, if I select D dimension and table Y's measures at the same time in BI Answer, result returns no data. Hence, I can't compare table X and table Y's results with selection of D dimension.
Is there any solution to solve this problem?
Edited by: TomChan on Jun 3, 2009 9:36 AM

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1. It's a prerequisite to use a star schema to build a EUL or I can/ must used a Relational Schema?
2. The OLAP Option of Discoverer Plus work with an EUL or with a star schema
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This is a more suitable question for the Business Intelligence (EBS).
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~ Madrid.

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Hello practitioners,
We are new to OBIEE and started some weeks ago. We are a two-men team. One guy doing all the data design and the other for everything around Answers.
So it happens regularly that the other guy has to ask the one guy, about the exact definition and meaning of data-fields, he wants to use in Answers.
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Question:
What tools and methods do you use to document the star-schemas and dashboards?
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Hi Turalf,
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Im pretty sure you can expose comments from the RPD into this also.
http://obiee101.blogspot.com/2008/12/obiee-metadata-dictionary.html
Maybe you could look at the ODI - OBIEE data lineage also, it provides "report to source" mapping info :
http://www.oracle.com/technology/obe/fusion_middleware/ODI/OBI-ODI_Lineage/OBI-ODI_Lineage.htm
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Star Schema and Oracle 11gR2 ?

Star Schema and Oracle 11gR2 ?
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Hi,
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If you find those 10 conditions, please post them here. I'm curious to learn about them!
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Carsten.

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Hi,
I'm learning the basic concept of data warehousing and I've some question in this regards.
1) I want to know, are we have to first create star schema and tables according to that star schema in dbms, from that star schema we have to built cubes OR we directly build cubes from extracted data through OLTP systems.
2) secondly, when we create cubes, in which formate they are store in dbms and are they directly load in the memory at run time?
Please clarify me in these concepts as new to data warehouse I've certain concept misunderstanding in this regards. Answers will be highly appreciated
Regards,
D.Abbasi

1) I want to know, are we have to first create star schema and tables according to that star schema in dbms, from that star schema we have to built cubes OR we directly build cubes from extracted data through OLTP systems. Star schema is the Dimensional Modeling Technique and that need to considered while creating Dimension and not cubes.
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2) secondly, when we create cubes, in which format they are store in dbms and are they directly load in the memory at run time?Cubes and Dimensions are stored in Database in some different format.
This is the nice article regarding how the data is store in DB,
http://www.dba-oracle.com/t_olap_dimensions_cubes.htm
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Nawneet
Edited by: Nawneet on Mar 29, 2010 5:47 AM
Edited by: Nawneet on Mar 29, 2010 5:50 AM

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Two Fact tables with Different set of Dimension Tables

Here is my scenario:
I got two fact tables: X and Y (actually, they are the same tables, but with different level of data)
and four dimension tables: A, B, C, D
X joins relationship to all dimensions (A, B, C, D).
Y joins relationship to only A, B, C, but no D.
When I select dimension A, B and C together with fact tables X and Y in BI Answer, result is displayed and compared.
However, if I select dimension D together with fact tables X and Y, only data from fact table X is displayed. There is no result displayed for fact table Y. I know that this is because fact table Y does not join to dimension D.
If the above relationship unchanged, how can I display both X and Y's result in BI Answer when dimension D is selected?

Thanks for all your replies.
Actually, I've tried the solutions you guys mentioned. Generally speaking, the result should be displayed. However, my scenario is a little bit tricky.
table Y's figures are not the aggregation of table X for D dimension. Instead, table Y's figures include not only D dimension total, but also others (others do not mean A, B, C dimension). For example, table Y stores all food's figure, while table X stores only drink's figure. D dimension is only about drink's detail. In my scenario, other foods' figure is not provided.
So, even if I set D dimension to all/total for table X, table X's result is still not the same as table Y.
Indeed, table Y does not have a column key to join to D dimension's key. So, if I select D dimension and table Y's measures at the same time in BI Answer, result returns no data. Hence, I can't compare table X and table Y's results with selection of D dimension.
Is there any solution to solve this problem?
Edited by: TomChan on Jun 3, 2009 9:36 AM

Using 2 fact tables with different granularity against calendar dimension

Hello gurus,
I have a requirement to provide a report to show the consumption of available capacity per month and also YTD.
I have two fact tables:
Fact table ‘Capacity’ with columns:
- Site_id
- Month_id
- Capacity
Ie.
001, 2010M01, 50
001, 2010M02, 50
001, 2010M12, 75
002, 2010M01, 60
002, 2010M02, 65
002, 2010M12, 80
Etc
Fact table ‘Consumption’ with columns
- Site_id
- Day_id
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Ie
001, 20100101, 2
001, 20100102, 3
001, 20100131, 1
001, 20100201, 5
001, 20100212, 6
001, 20100228, 4
Etc
As can be see above, my ‘Capacity’ table contains monthly volumes, and the ‘Cunsumption’ table contains daily volumes.
My Calendar dimension is straightforward:
Year
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Month_id
Day_id
Ie
2010, 2010Q1, 2010M01, 20100101
2010, 2010Q1, 2010M01, 20100102
2010, 2010Q1, 2010M01, 20100103
2010, 2010Q1, 2010M01, 20100104
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Site_id
Site_name
Group
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     Calendar.Day_id = Consumption.Day_id
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- Created Calendar hierachy:
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          Dimension Calendar: Logical Level = Month
     Fact table Consumption:
          Dimension MfgSite: Logical Level = Site
          Dimension Calendar: Logical Level = Day
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Capacity.Capacity
Consumption.Consumption
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I then built a few reports to test it out and found that I have an issue with the Capacity object: When I build a simple report to show capacity per month:
SiteName, Month, Capacity
the capacity for each month is multiplied by the number of calendardays in that months, so I get
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Etc
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Unable to navigate requested expression: ToDate(Capacity:[DAggr(Capacity.Capacity by [ Calendar.Year, Calendar.Month_id, MfgSite.Site_id, MfgSite.SiteName] )], [Level Year]). Please fix the metadata consistency warnings. (HY000)
Did I miss any steps? Any help is greatly appreciated!
Thanks!
Randall

hi in the capacity fact table remove the level set for the calendar dim and see.

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Hello Guys,
I just heard from one of my colleagues that its wise to
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Thanks

"Usually the date is stored in sales table or product table.
ut here why they created separate Dimension table for date(Dim_date)? "
You should provide the link.
A good place to start with the basic concepts is :
http://www.ralphkimball.com/
Pick up some of his books and start going through them.
My recommendation would be
The Data Warehouse Toolkit, 2nd Edition: The Complete Guide to Dimensional Modeling
John Wiley & Sons, 2002 (436 pages
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Hi Guys,
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Shaz

I have designed a Star schema for one of my datamart and my client is after me suggesting that over that I should create a MV to provide a consolidated view. I am trying to convience my client not to do so with the points as below:You are convincing them to NOT do one of the the things materialized views were originally introduced to provide?
I'm purposely going all the way back to 8i documentation here to emphasize the point.
http://docs.oracle.com/cd/A87860_01/doc/server.817/a76994/qr.htm#35520
" Overview of Query RewriteOne of the major benefits of creating and maintaining materialized views is the ability to take advantage of query rewrite, which transforms a SQL statement expressed in terms of tables or views into a statement accessing one or more materialized views that are defined on the detail tables. The transformation is transparent to the end user or application, requiring no intervention and no reference to the materialized view in the SQL statement. Because query rewrite is transparent, materialized views can be added or dropped just like indexes without invalidating the SQL in the application code. "
>
The theory behind query rewrite is this: have them build their queries based on your star schema (or you a build a traditional view that does that), then build a materialized view that mirrors the query/view. If the materialized view is refreshing or not up-to-date, their queries will run (more slowly) against the star schema. If it is up-to-date it will be used instead, providing faster results.
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Hello,
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Hi
I t is imperative that you refer some documentation related to BI Modeling. There are a couple of good docs. available which explain in detail about building an Infocube based on star schema to meet certain reporting requirement.
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Hi Rajendra and Visakh16,
Based on your input provided to this thread, I would like to ask a question just to fine-tune my knowledge regarding data modelling. In Darren’s case I guess his date dimension only store dimension records up to day level granularity. Now the requirement
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Using two facts of two different star schemas and conformed dimensions

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