Star Schemas with designer 6.0
How can I easily create star schemas for a Datawarehouse in Designer6? Where can I still find documentation for such release?
Mauro
Mauro,
You should be able to create start schemas - search in the online help for all references to data warehousing
and star schemas. There should be a few topics.
Regards,
Dominic
Designer Product Management
Oracle Corp
Similar Messages
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Relational Star Schema with oWB 10g
Hi,
It is an interesting forum. I like to explore the different approached to build ETL using OWB to load Star Schema built around Oracle 10g relational structures.
How do we take advantage of additional features of Oracle DB 10g and OWB 10gR2?
What features does help? Which one should stay away from?
Thanks in advance.
RamHi ,
You can use Oracle SQL Developer Data Modeler .
SQL Developer Data Modeler provides a full spectrum of data and database modeling tools and utilities, including modeling for Entity Relationship Diagrams (ERD), Relational (database design), Data Type and Multi-dimensional modeling, full forward and reverse engineering and DDL code generation. The Data Modeler imports from and exports to a variety of sources and targets, provides a variety of formatting options and validates the models through a predefined set of design rules.
Oracle SQL Developer Data Modeler can connect to any supported Oracle Database and is platform independent
http://www.oracle.com/technology/products/database/datamodeler/index.html
Thanks,
Sutirtha -
Resolving loops in a star schema with 5 fact tables and 6 dimension tables
Hello
I have a star schema, ie 5 FACT tables and 7 dimension tables, All fact tables share the same dimension tables, some FACT tables share 3 dimesnsions, while other share 5 dimensions.
I did adopt the best practices, and as recommended in the book, I tried to resolve them using Context, as it is the recommended option to Alias in a star schema setting. The contexts are resolved, but I still have loops. I also cleared the Multiple SQL Statement for each context option, but no luck. I need to get this resoved ASAPHi Patil,
It is not clear what exactly is the problem. As a starting point you could set the context up so that it only covers the joins from fact to dimension.
Fact A, joins Dim 1, Dim 2, Dim 3, and Dim 4
Fact B, joins Dim 1, Dim 2, Dim 3, Dim 4 and Dim 5
Fact C, joins Dim 1, Dim 2, Dim 3, Dim 4 and Dim 6
Fact D, joins Dim 1, Dim 2, Dim 3, Dim 4 and Dim 7
Fact E, joins Dim 1, Dim 2, Dim 4 and Dim 6
If each of these are contexts are done and just cover the joins from fact to dim then you should be not get loops.
If you could lay out your joins like above then it may be possible to specify the contexts/aliases that should work.
Regards
Alan -
Distinctcount across star schema with boolean filter
Hi,
I have a fact table with CustomerNo, DateKey, ProductKey, SupplierKey, Sales.
This is related to a Calendar table, Product, and Supplier Table.
I'm trying to calculate a distinct count of customer where the sales = 0 and keeping the original filter conditions on related tables.
I've tried :
Calculate(Distinctcount(fact[CustomerNo), Fact[Sales]=0)
The figures are wrong. It's hard for me to evaluate what rows are actually being returned due to the size of the table. I think it may be related to the the DistinctCount running a groupby first and the filter being run second.
So I tried :
Calculate(Distinctcount(fact[CustomerNo), Filter(Fact, Fact[Sales]=0))
This returns the same value as the one above.
It's very weird as the slicers on the Pivot do interact with the measure so I know the measures are keeping the existing filter contexts.
Any ideas what is happening?
Lee Hawthorn ACMA, CGMA View my Performance Management blog at leehbi.comwell, the formula you provided is correct and should return the correct result
its hard to say why it would return wrong results without knowing/seeing the data
the only thing i could think of is the following:
a customer made two sales 1) with Sales=123 2) with Sales=0
the formula would of course count that customer as a distinct customer with Sales=0
maybe thats the reason for your "wrong" results?
you may also check this link: http://www.daxpatterns.com/distinct-count/
hth,
gerhard
Gerhard Brueckl
blogging @ http://blog.gbrueckl.at
working @ http://www.pmOne.com -
Normalized (3NF) VS Denormalized(Star Schema) Data warehouse :
what are the benefits of normalized data warehouse (3NF) over the denormalized (Star schema)?
if DW is in the 3NF then is need to create the seprate physical database which contains several data marts( star schema)with physical tables, which feeds to cube or create the views(SSAS data source view) on top of 3NF warehouse of star schema which feeds to
cube?
please explin the pros and cons of 3NF and denormalized DW.
thanks in advance.
Zaim Raza.Hi Zaim,
Take a look to this diagram:
1) Normally, 3NF schema is typical for ODS layer, which is simply used to fetch data from sources, generalize, prepare, cleanse data for upcoming load to data warehouse.
2) When it comes to DW layer (Data Warehouse), data modelers general challenge is to build historical data silo.
Star schema with slow changing facts and slow changing dimensions are partially suitable.
The DataVault and other similar specialized methods provides, in my opinion, wider possibility and flexibility.
3) Star schema is perfectly suitable for datamarts. SQL Server 2008 and higher contains numerous query analyzer improvements to handle such workload efficiently. SQL Server 2012 introduced column stored indexes, that makes possibility to
create robust star model datamarts with SQL Query performance comparable to MS OLAP.
So, your choice is:
1) Create solid, consistent DW solution
2) Create separate datamarts on top of DW for specific business needs.
3) Create necessary indexes, PK, FK key and statistics (of FK in fact tables) to help sql optimizer as much as possible.
4) Forget about approach of defining SSAS datasource view on top of 3NF (or any other DWH modeling method), since this is the way to performance and maintenance issues in the future. -
What happens when i remove Dimension table in extended star schema
*how to integrate the flex builder web dynpro and xcelsius?
i found some scenarios like when the content of the table change the chart will changes for the changed data in the table using flash islands and web dynpro.
my scenario is like this.
when i changed the chart with sliders automatically the content in the table will update to the chart level ? but both table and chart will be in the same dashboard. how can i work out this scenario using flash islands, flex and web dynpro>
thanks in Advance*Hi Sateesh,
Please go through this URL you will get overall Idea about Extended Star schema with DIM ID's,SID's and Data flow.
http://help.sap.com/saphelp_nw70/helpdata/EN/8d/2b4e3cb7f4d83ee10000000a114084/frameset.htm
http://help.sap.com/saphelp_nw70/helpdata/EN/8d/2b4e3cb7f4d83ee10000000a114084/frameset.htm
http://help.sap.com/saphelp_nw70/helpdata/EN/8d/2b4e3cb7f4d83ee10000000a114084/frameset.htm
I hope it will help you.
Regards
Suresh B.G. -
Understanding Star Schema Operations
Hi All,
I worked on Oracle Answers and have knowledge on Data Warehousing concepts. I have enough oracle documentation on OLAP, OBIEE, Data Warehousing.
But i 'm not able to understand the star schema concepts in and out. I'm lost on all documents, where i'm getting the simple answer on the following topics:
1. Is it necessary to create dimensions using CREATE DIMENTION or it can be a simple relational table structure with CREATE TABLE statement?
2. What will be the steps to create a very basic/simple star schema using DML statements not using any tool?
3. Where I can get very basic level step by step tutorial to create a very simple star schema by sql -> loading test data by sql commands -> then what queries we can use to get BI reports or using OBIEE to create a simple rpd.
Please give me some idea on this as I have to create a small OBIEE repository where i have to do create the warehouse and ETL process, everything.
Pls advise.
Thanks in Advance.
SudiptaNo my question was on creating the star schema. If i have to create a very simple star schema then can I create the star schema with the following relational tables?
create table dim_products (
product_id number primary key,
product_name varchar2(32),
brand varchar2(32),
category_name varchar(32),
sub_category_name varchar2(32)
create table dim_time (
time_id number primary key,
selling_date date,
selling_day number(2),
selling_month varchar2(12),
selling_Quarter varchar2(6),
year number(4)
create table dim_region (
region_id number primary key,
store_name varchar2(32),
city_name varchar2(32),
state_name varchar2(32),
country_name varchar2(32),
region_name varchar2(32)
create table fact_sales (
sale_id number primary key,
region_id number ,
time_id number ,
product_id number ,
unit_sold number,
constraint fact_sales1 foreign key (region_id) references dim_region (region_id),
constraint fact_sales2 foreign key (time_id) references dim_time (time_id),
constraint fact_sales3 foreign key (product_id) references dim_products (product_id)
Or I have to create the DIMENSIONS explicitly, in order to building the hierarchy levels?
Regards
Sudipta -
Design Fixed Assets Star Schema from OLTP DB
Hi,
Scope : Design Fixed Assets logical Star Schema for Demonstrate with OLTP tables
Our platform is Oracle 10g Forms and Reports deployed on Oracle 10g App Server._ At the moment we don’t have data warehouse constructed. We are pumping OLTP Data into Staging DB thru jobs and then by using materialized views getting the data in DWH DB which is in progress.
OBIEE 10g installed and working fine for testing.
We are planning to implement OBIEE for Reporting. As a starting point I would like to design Fixed Assets star schema to demonstrate FA reports in OBIEE from OLTP Tables.
FA- OLTP Tables:_
AC_UNIT_MASTR – Business Units
AC_ACNT_MASTR - Nominal Codes
AC_COST_CENTR_MASTR - Departments
AC_MANTN_ASTS - Assets transaction table
AC_AST_BAL_DETLS – Period wise Asset summary
AC_AST_BAL_DETLS_V - View
To achieve this
1).Import tables in physical layer and set physical joins
2).identify and create dimensions and set complex joins and then move to presentation layer.
Please suggest best approach to design Repository
Thanks
Regards,
Kulkarni
Edited by: hai_shailesh on Jan 25, 2012 11:36 PM
Edited by: hai_shailesh on Jan 25, 2012 11:38 PM
Edited by: hai_shailesh on Jan 25, 2012 11:39 PMHi Saichand,
Thanks for the response.
Already i referred that doc and completed practically. now i have to work on Finance data . as a starting point working with Fixed Assets module. already i designed centralised fact with dimensions as below
in physical&BMM layer defined relationship as below()
AC_UNIT_MASTR_D --> AC_AST_BAL_DETLS_F
AC_ACNT_YEAR_MASTR_D --> AC_AST_BAL_DETLS_F
AC_ACNT_PERD_MASTR_D --> AC_AST_BAL_DETLS_F
AC_COST_CENTR_MASTR_D --> AC_AST_BAL_DETLS_F
AC_AST_GRP_MASTR_D --> AC_AST_BAL_DETLS_F
AC_AST_SUBGRP_MASTR_D --> AC_AST_BAL_DETLS_F
and
AC_ACNT_YEAR_MASTR_D --> AC_ACNT_PERD_MASTR_D
When iam trying to create a dimension for Periods(AC_ACNT_PERD_MASTR) , Periods dimesnion created with two tables
AC_ACNT_YEAR_MASTR_D,AC_ACNT_PERD_MASTR_D
Please advice..
Regards,
Kulkarni -
Star schema design, metrics dimension or not.
Hello Guys,
I just heard from one of my colleagues that its wise to
have an "KPI" or "metrics" dimension in my DWH star schema (later used in OBIEE).
Now, we have quite a lot of data 100 000 rows per day (botton leve, non-aggregated, the aggregations are obviously far less then that, lets say 200 rows per day) and
we have build pre-aggregated data marts for each of the 5 very static reports (OBIEE Publisher).
The table structure is very simple
e.g.
Date,County,NumberofCars,RevenuePerCar, ExpensesPerCar, BreakEvenPerCar, CarType
One could exclude the metrics "NumberofCars","RevenuePerCar", "ExpensesPerCar", "BreakEvenPerCar"
and put them into a metrics dimension.
MetricID Metric
1 NumberofCars
2 RevenuePerCar
3 ExpensesPerCar
4 BreakEvenPerCar
and hence the fact table design would be simpler.
Date,County,MetricID,Metric, CarType
Disadvanatages: A join is required
We would have to redesign our tables
tables are not aggregated anymore for specific metric types
if we notice performance is bad, we would need to go back to the old design
Advantages : Should new metrics appear, we dont have to change the design of the tables
its probably best practice
Note: date, country and cartype are already dimensions. we are just missing one to differentiate the metrics/KPI's
So I struggle a bit, what should I do? Redesign, or stick to the way I have done it, having
performance optimization in mind.
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
Good Luck., -
Hi,
I know that in classical star schema the dimension tables sits within the info cube and so we cannot use this dimension table in any other cube we need to have separate dimension table for that cube thought it might be having same data. I also know to over come this redundancy extended star schema came into picture where we have SID table and we keep the dimension table out of the cube and reuse the dimension tables across many cubes.
Now what i don't understand is that instead of having Separate SID tables for linking the dimension and fact tables why cant we make the DIMENSION table generic and keep them out of the infocube so that we can same the same dimension table for many infocube in this case we wont need SID tables.
suppose i have one info cube which has dimension vendor material and customer and its keyfigure is quantity and price and i have a separate infocube which has dimesnion material customer and location and its key figure is something else ......so here in why cant i keep the dimensions out of the infocube and use the dimension material customer for both infocube.Your dimension tables are filled based on your transaction data - which is why dimension table design is very important you decide to group related data for the incoming transaction data into your dimension tables .
The dimension tables have SIDs which in turn point to master data = in the classic star schema - the dimension tables are outside the cube but the dim tables have the master data within them whhich is overcome using the extended star schema.
The reason why dimension tables can be reused is that the dim IDs and SIDs in the simension table correspond to the transaction data in the cube - and unless the dim IDs in both your cubes match you cannot reuse the dim tables - which means that you have exactly the same data in both the cubes - which means you need not have two cubes with the same data.
Example :
Cube 1 : Fact Table
Dim1ID | DIM2ID | KF1
1|01|100
2|02|200
Dimension Table : Dim 1 ( Assumin that there are 2 characteristics in this dimension ) - here the DIM1ID is Key
Dim1ID | SID1 | SID2
1|20|25
2|30|35
Dimension Table Dim 2 - Here the Dim2ID field is key
Dim2ID| SID1 | SID2| SID3
01| 30| 45
02|45|40
Here the Dim IDs for the cube Fact table are generated at the time of load and this is generated from the NRIV Table ( read material on Number Ranges ) - this meanns that you cannot control DIM ID generation across cubes which means that you cannot reuse Dimension Tables -
How you we design and create a star schema in Oracle BI?
We can use Informatica to generate ETL. But how do we design the star-schema?? Is there a design tool like Oracle Designer??
What is the purpose of the DAC??Hi,
You can handle the star schema design in the BMM layer. No separate tool for that.
Refer-
http://gerardnico.com/wiki/data_modeling/star_schema
DAC-
Data Warehouse Application Console (DAC) works together with Informatica to acomplish the ETL for pre-packaged BI application.
- DAC publish the changes from OLTP
- Informatica extracts the changes from the change log published by DAC as well as from the base table
- Informatica load the data to the stage tables and the target tables in the data warehouse
- DAC manage the performance by dropping indexes, truncating stage tables, rebuilding the indexes, and analyzing the tables during the process
If you do not use DAC, you have to write your own custom change capture process and need to redesign from scratch an ETL method that allow the restart of the ETL process from point of failure at record level. The biggest saving is that DAC can survive during the upgrade , while your custom processes cannot.
Refer-
http://obieetraining11.blogspot.in/2012/06/how-to-use-dac-source-system-parameter.html
Hope this helped/ answered.
Regards
MuRam
Edited by: MuRam on Jun 25, 2012 2:37 AM -
Error with creating star schema using HsvStarSchemaACM
Hi,
I am trying to create a star schema using the API HsvStarSchemaACM. But when calling the create function of API, i get the below exception. Exception from HRESULT: 0x80040251 (A general error occurred while trying to obtain a database Reader/Writer lock). Is this something to do with the parameters passed and its connections(connection works fine and createstarschema is running thru workspace).
Any solutions to this is more welcome.
Thanks,
LoguCan you provide details on HsvStarSchemaACM API? How is it related to ODI?
-
Hi All,
I have a star schema in place with 8 dimension and 1 fact table.
But due to some specific requirement, I need to denormalize the schema. I want to copy all fields from all dimension tables to the fact table.
I know this sounds bad but I have to do it. pls dont ask why..
Now, the same can be done using a materialized view but the problem in MV is there are fields which are present in 2 or more table with the same column name, due to which I cant create a MV.
Is there some other way to achieve this goal.
BRK.I have too many records which is affecting the performance of the database.
But now its raising performance problems.Your application had a performance problem. Somebody guessed that a star schema would solve the problem. But it hasn't. So now you intend to implement some spavined variant on star schema because somebody has suggested that complete de-normalisation might solve the problem.
Is this a demonstrable fact (you have benchmarks and explain plans to justify it) or just a guess?
I know how difficult this sort of thing can be, because I've been working through some similar scenario for a while now. The important thing is get some decent metrics on your application. Use statspack. Use the wait interface. Find out where your application is spending its time and figure out what you need to do to reduce the waits. Benchmark some alternatives. This may result in you having to re-write your code but at least you'll be doing so in the knowledge
Cheers, APC
Blog : http://radiofreetooting.blogspot.com/ -
Hi,
What are the factors or the things that we should consider while designing star schema ?
Thanks
VaishaliVaishali,
The major things to be considered while designing start could be ..
1. Proper maintenance of Master data which will be shared across all the infocubes.
2. Deciding upon dimensions. Which characteristics should be assigned to which dimension? Try to reduce the number of dimensions.
3. Design deimensions based upon the characteristic relation 1:M...
4. If the char has more no of values for eg, document number which come in huge volumes to BW that can be designed as Line item dimension instead of assigning it to a dimension.....
Hope this helps you..... -
Need help with an extended star schema.
I have the following data in spreadsheet form and I need to transpose this into an extended star schema in order to prdouce my characteristics and key figures, however I'm having a little trouble understanding where to include the Product Group in the star schema and also what to do with the Sales Doc (Invoice Number) in the sales information spreadsheet.
I need to summarise the data into the following also:
1. Total quantity and revenue for each Channel and product group
2. Total quantity and revenue for each Channel and product group (July 2009 to September 2009)
3. Total Quantity and Revenue for iphone sales
So my question in short is what would the star schema look like? I'm hoping somebody can help me over this hurdle.
The following are the details from the spreadsheet:
Product Details (Attributes)
File Name: Product_Details.csv
Structure FieldName Length Description
ProdID 5 Uniquely identifies a product
PG_Group 20 Identifies products in specific groups (Navigational field)
Sample Data
ProdID,PG_Group
PDS01,COMPUTER
PDS02,COMPUTER
PDS03,COMPUTER
PDS04,ACCESSORIES
PDS05,ACCESSORIES
PDS06,ACCESSORIES
PDS07,ACCESSORIES
PDS08,HARDWARE
Product Description (Text)
File Name: Product.csv
Structure FieldName Length Description
ProdID 5 Uniquely identifies a product
Prod_Desc Medium Text Represents the product description
(Navigational field)
Language 2 Represents the language descriptor
Sample Data
ProdID,Prod_Desc,Language
PDS01,Notebook Speedy I,EN
PDS02,Notebook Speedy II,EN
PDS03,PC Thinkbox I,EN
PDS04,USB Adaptor,EN
PDS05,iPhones PX2,EN
PDS06, Stereo Kit,EN
PDS07,Camera Connector,EN
PDS08,USB Storage,EN
Transactional Data
Sales information
File Name: Sales.txt
Structure FieldName Length Description
Product 5 Uniquely identifies a product
Sales Doc 4 Sales Document number (Invoice Number)
Calendar Year 8 YYYYMMDD format
Channel 1 Represents the distribution channel the product was sold by
Quantity 4 Numeric value indicating the number of each product sold on a specific sales document
Unit 2 Refers the unit specified by the quantity
Revenue 8 Refers the sales amount of a specific product on a specific sales document
Currency 3 Relates the revenue currency type
Sample Data
Product;Sales Doc ,Calendar Day,Channel,Quantity,Unit;Revenue,Currency
ZD_PROD,0DOC_NUMBER,0CALDAY,ZD_CHAN,ZD_QTY,0UNIT,ZD_REV,0CURRENCY
PDS07,7389,20090705,A,95,EA,151905,USD
PDS08,7389,20090705,A,115,EA,264385,USD
PDS02,7473,20090706,B,55,EA,3580445,USD
PDS01,7472,20090706,C,110,EA,604989,USD
PDS02,7472,20090706,C,43,EA,2799257,USD
PDS03,7472,20090706,C,75,EA,4507425,USD
PDS04,7472,20090706,A,339,EA,301032,USD
PDS06,7472,20090706,A,120,EA,47976,USD
PDS01,7473,20090718,D,55,EA,3024945,USD
PDS02,6845,20090806,B,30,EA,195297,USD
PDS07,6877,20090807,C,800,EA,12792,USD
PDS08,6877,20090807,C,250,EA,57475,USD
PDS03,6912,20090812,C,250,EA,1502475,USD
PDS04,6900,20090812,B,70,EA,6216,USD
PDS01,6899,20090812,C,12,EA,659988,USD
PDS04,6899,20090812,D,55,EA,4884,USD
PDS04,7479,20090815,C,80,EA,7104,USD
PDS05,7479,20090815,C,300,EA,70497,USD
PDS05,6809,20090818,A,1000,EA,234990,USD
PDS06,6809,20090818,A,130,EA,51974,USD
PDS03,6831,20090822,C,15,EA,901485,USD
PDS04,6831,20090822,C,500,EA,4440,USD
PDS03,6830,20090822,C,125,EA,7512375,USD
PDS06,6830,20090822,C,400,EA,15992,USD
PDS04,6841,20090825,C,53,EA,47064,USD
PDS05,6841,20090825,C,350,EA,822465,USD
Distribution Channel
Channel (text)
File Name: Channel.csv
Structure FieldName Length Description
ChanID 1 Uniquely identifies a specific distribution channel
Chan_Desc Medium
Text Full name of each distribution channel
(Navigational field)
Sample Data
ChanID, Chan_Desc
A,Phone
B,Fax
C,Internet
D,Other
Star Schema Model:Potentially the issue may be the combination of actual distance and the presence of any Wi-Fi interference at the location of the AirPort Express that may be the culprit here. The bottom line is you would want the Express to be within a 25+ dB range of the Extreme to be sure that it can consistently stay connected to it.
For more details on proper base station placement, check out the following AirPort User tip. Please post back your results.
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