ROLAP skip level dimension support - CWM2?

Dear all
We have a client with an interesting problem. I was wondering if the group could offer any feedback on this design question, where we think it involves a concept called 'skip levels'. The client is using Oracle 9.0.2 with their data mart cube held as ROLAP. Our first thoughts are that what they want to do is better served by using a true OLAP tool such as Oracle Express, or Oracle 9i OLAP, which deals with skip level dimensions easier. Anyway, here's the problem :
"For our warehouse project, we need some dimensions (initially: account, company) that use a skip level hierarchy. This means that the lowest level dimensions are of the same level (G/L account or company) and they need to roll up in a structure of varying levels, before they come together again in a highest level.
Ideally, we would like to use a data structure that can be used transparently by the user and allows for rollups of amounts through the dimension. We would like to be able to populate the dimension through OWB and to query the data using both Crystal reports v9 and BI beans and possibly other tools that recognize the Oracle data warehouse concept.
The two solutions we are aware of are:
1. Insert Dummy levels:
This is not a nice solution but is will work and it is simple.
2. Insert a helper table that contains the higher level account with all the children (as per Ralph Kimball)
This seems a cumbersome solution but I am sure it would work also. The question is how the Oracle's BI beans and the CWM2 metadata would recognize this and how we can make this transparent to the user.
I am sure there are other solutions to the problem. It seems like the problem would be solved by the next release of Oracle (9.0.3?), which allows us to deal with skip level hierarchies through CWM2 (which I believe this is). The solution we choose should also allow us to easily upgrade to the new skip level hierarchy, which I would expect to be easier to use then the above."
The main thing to bear in mind here is that they want to implement a ROLAP solution, using Oracle 9i tables, dimensions and heirarchies. It also has to work with Oracle Warehouse Builder, take advantage of the CWM2 metadata (if possible) and work with the BI Beans.
Any thoughts on this? Does anyone know how Oracle are going to cater for skip-level dimensions with the next release? Is this through the improved support for the CWM2 metadata standard for ROLAP cubes, or is the customer best of going to the true OLAP 'Analytic Workspace'? If we ignore a MOLAP solution, what's the best way of dealing with this, in such a manner that it's transparent to query tools, and isn't too much of a 'hack'?
Many thanks in advance,
Mark Rittman
Mark Rittman
Consulting Manager, Plus Consultancy
[email protected]
[email protected]--------------

Similar Messages

Skip Level Dimensions

Dear all
We have a client with an interesting problem. I was wondering if the group could offer any feedback on this design question, where we think it involves a concept called 'skip levels'. The client is using Oracle 9.0.2 with their data mart cube held as ROLAP. Our first thoughts are that what they want to do is better served by using a true OLAP tool such as Oracle Express, or Oracle 9i OLAP, which deals with skip level dimensions easier. Anyway, here's the problem :
"For our warehouse project, we need some dimensions (initially: account, company) that use a skip level hierarchy. This means that the lowest level dimensions are of the same level (G/L account or company) and they need to roll up in a structure of varying levels, before they come together again in a highest level.
Ideally, we would like to use a data structure that can be used transparently by the user and allows for rollups of amounts through the dimension. We would like to be able to populate the dimension through OWB and to query the data using both Crystal reports v9 and BI beans and possibly other tools that recognize the Oracle data warehouse concept.
The two solutions we are aware of are:
1. Insert Dummy levels:
This is not a nice solution but is will work and it is simple.
2. Insert a helper table that contains the higher level account with all the children (as per Ralph Kimball)
This seems a cumbersome solution but I am sure it would work also. The question is how the Oracle's BI beans and the CWM2 metadata would recognize this and how we can make this transparent to the user.
I am sure there are other solutions to the problem. It seems like the problem would be solved by the next release of Oracle (9.0.3?), which allows us to deal with skip level hierarchies through CWM2 (which I believe this is). The solution we choose should also allow us to easily upgrade to the new skip level hierarchy, which I would expect to be easier to use then the above."
The main thing to bear in mind here is that they want to implement a ROLAP solution, using Oracle 9i tables, dimensions and heirarchies. It also has to work with Oracle Warehouse Builder, take advantage of the CWM2 metadata (if possible) and work with the BI Beans.
Any thoughts on this? Does anyone know how Oracle are going to cater for skip-level dimensions with the next release? Is this through the improved support for the CWM2 metadata standard for ROLAP cubes, or is the customer best of going to the true OLAP 'Analytic Workspace'? If we ignore a MOLAP solution, what's the best way of dealing with this, in such a manner that it's transparent to query tools, and isn't too much of a 'hack'?
Many thanks in advance,
Mark Rittman
Mark Rittman
Consulting Manager, Plus Consultancy
[email protected]
[email protected]--------------

As part of my search i've uncovered an article by Ralph Kimball on using 'helper tables' to deal with ragged hierarchies.
http://www.dbmsmag.com/9809d05.html
This advocates using a table between the fact table and the dimension. Quoting from Mr. Kimball;
"You can solve this modeling problem by inserting a helper table between the dimension table and the fact table, as shown in Figure 3 (http://www.dbmsmag.com/9809d05.html#fig3). Amazingly enough, you don't have to make any changes to either the dimension table or the fact table; you just rip the join apart and insert the helper table.
The helper table contains one record for each separate path from each node in the organization tree to itself and to every node below it. There are, then, more records in the helper table than there are nodes in the tree. In Figure 3 we need a total of 43 records in the helper table. See if you can work this out.
Each record in the helper table contains the fields:
- Parent Customer Key
- Subsidiary Customer Key
- Depth From Parent
- Lowest Flag
- Topmost Flag.
If you are descending the tree from certain selected parents to various subsidiaries, you join the dimension table to the helper table and the helper table to the fact table with the joins as shown in Figure 3. The Depth From Parent field counts how many levels the subsidiary is below the parent. The Lowest Flag field is True only if the subsidiary has no further nodes beneath it. The Topmost Flag field is True only if the parent has no further nodes above it.
The beauty of this design is that you can place any normal dimensional constraint against the Customer dimension table and the helper table will cause all the fact table records for the directly constrained customers plus all their subsidiaries to be correctly summarized. In other words, you can use your standard relational databases and your standard query tools to analyze the hierarchical structure."
My question is - has anyone tried to implement this with OWB, or with the Oracle ROLAP data warehouse in general, reporting through Discoverer or BI Beans? Any opinions?
thanks
Mark

Help with Skip Level dimensions in OWB 10.2 (Paris)

Hi all,
I'm trying to understand how to set up and use a skip level dimension in OWB 10.2. A simplified version of my hierarchy would be:
Plant - Equipment - Assembly - Item
Where Some Items connect directly to equipment and others connect to assemblies. How sould I define this in the Dimension wizard or editor in OWB?
Can I create a single dimension hierarchy and in the Item level put Skip Level as "Equipment"?
OR
Do I need 2 hierarchies - one Plant-Equipment-Assembly-Item and the other Plant-Equipment-Item?
There is an example in the Users guide that created 2 hierarchies -
TOTAL-GROUP-PRODUCT and TOTAL-PRODUCT
In the example, they show the PRODUCT in TOTAL-PRODUCT setting the skip level field. I don't understand why that is necessary if it is 2 seperate hierarchies.
Any help/guidance would be appreciated!
Thanks,
Mike

Hi Donna,
Perhaps JP can expand on his answer. In my case, I did go the route of seperate hierarchies. It is a bit of work defining multiple hierarchies and my example was much simplified. We actually have about 8 levels in the primary hierarchy and 6 levels in the second. It does work well with the cubes by using 2 roles for the dimension - one for each hierarchy.
I saw that truly "ragged hierarchies" or "level hierarchies" can be defined in OWB and deployed as MOLAP but MOLAP has quite a few drawbacks - no SCDs and requires analytic workspaces etc. I haven't done anything with these yet.
Our data is a classic manufacturing Bill of Material so the level hierarchy would be the easiest to manage, though I'm not sure how easy it would be to report on! I do want to shield my end-users from CONNECT-BY madness.

Design a dimension with skip-level hierarchy and its ETL

Hi gurus,
I'm trying to understand how to set up and use a skip level dimension and its corresponding mapping in OWB 11.2.
A simplified version of my hierarchy would be like Total-Brand-LOB-Product where Some Products connect directly to Brand and others connect to LOB.
My first question is about designing this kind of dimension in OWB. Is it better to create a single hierarchy with the Product level skipped to Brand level or 2 hierarchies - one Total-Brand-LOB-Product and the other Total-Brand-Product?
My second question is about creating its corresponding ETL mapping. Selecting each option above result in 2 FKs for Brand and LOB in Product level. What is the correct design to fill these 2 FKs?
Any help/guidance would be truly appreciated!
Thanks,
Iman

Hi, My problem is that in my report it is showing me that levels as -- A -> B -> C -> Null -> Null -> F, however I want to show data as A -> B -> C -> F, i.e the null valus(columns) should be skipped. Please help.
Thanks and Regards,
Deepak

Do BI Beans support ragged or skip-level hierarchies

Do BI Beans support ragged or skip-level hierarchies ?

Hi Alexander.
Well I am also a positive person ;)
Here it goes....
In the guide page 93/412
Oracle® OLAP
Application Developers Guide
Release 9.2.0.4.1
Part No. B10333-01
"Dimension Tables with Complex Hierarchies
If your source data is a star or snowflake schema, but the dimension tables include
any of the following variations, then use the CWM2 APIs:
-> Level columns containing NULLs, such as skip-level hierarchies
-> Multiple hierarchies with different base levels (sometimes called ragged
hierarchies)
-> Multiple hierarchies with values mapped to different levels
-> Parent-child dimensions
Choosing a Tool for Creating OLAP Catalog Metadata
If your schema contains parent-child dimension tables, then you must convert them
to level-based dimension tables. The CWM2 write APIs include a package for this
transformation."
You can use the next three steps to add different levels and do the mappings you want!
CWM2:
execute cwm2_olap_level.add_level_to_hierarchy
execute cwm2_olap_table_map.Map_DimTbl_HierLevel
execute cwm2_olap_table_map.Map_DimTbl_HierLevelAttr
Best regards.
Odds

Issue with Skip Level Hierarchy in OBIEE 11g

Hi,
I have implemented Ragged and Skip Level Hierarchy as explained in the links below in OBIEE 11g RPD.
(checked the 'Ragged' and 'Skipped Levels' check boxes)
http://www.rittmanmead.com/2010/07/obiee-11gr1-support-for-ragged-skip-level-value-based-hierarchies/
http://docs.oracle.com/cd/E17904_01/bi.1111/e10540/dimensions.htm#BABFBBFG
When the Presentation Hierarchy is dragged in the OBI Answers, the leaf level beyond the skip (null) levels is not shown in the report.
When any level finds intermediate null values, OBIEE is failing to show the existing value of the leaf level (Most Granular Level) or any values after Skipped Levels.
For example, following is the values in database for different levels of department hierarchy.
A -> B -> C -> Null -> Null -> F
The OBIEE Presentation Hierarchy can only drill down till C, not beyond that. (does not show the leaf level value 'F').
Could you please suggest whether I am missing any step?
Thanks.

Hi, My problem is that in my report it is showing me that levels as -- A -> B -> C -> Null -> Null -> F, however I want to show data as A -> B -> C -> F, i.e the null valus(columns) should be skipped. Please help.
Thanks and Regards,
Deepak

Problem with skip-level hierarchies

Hi,
I have created metadata using CWM2 procedures. These procedures allow define skip-level or ragged hierarchies.
I created skip-level hierarchies by setting null values to several keys in dimension table.
The result is... OLAP did not created cursor error, when I try to drill that hiuerarchy?
Why?
How to build BIBeans compatible skip-level hierarchies and?
My next question: Is it possible to use BIBeans with fact tables which contain embedded totals?
Slawek.

Hello Vicky,
Products created in R/3 can always be downloaded to CRM using the download object MATERIAL.
But products created in CRM could not be recovered back unless you archive them in CRM.
In order to delete the materials in CRM , you can use report COM_PRODUCT_DELETE_SINGLE or COM_PRODUCT_DELETE_ALL.
You can then download these materials from R/3.
Or you can have your own Z-report using the above standard report, where you can pass on the material id or range.
Also,please note that before executing these reports, you need to make an entry in table COMC_PR_TOOL_REG.
Hope this helps!
Best Regards,
Shanthala Kudva.

Aggregation plan/Skip level aggregation for model with a cumulative measure

I have planning data in the following format.
Project     Department Name     Task     Date          Units of work completed
PRO1     DEPARTMENT1          Task1     01/01/2008     12
PRO1     DEPARTMENT1          Task1     01/21/2008     3
PRO1     DEPARTMENT1          Task1     03/01/2008     8
PRO1     DEPARTMENT1          Task1               4
PRO1     DEPARTMENT1          Task2     01/21/2008     5
PRO1     DEPARTMENT1          Task2               9
PRO1     DEPARTMENT2          Task1     01/01/2008     20
PRO1     DEPARTMENT2          Task1     02/11/2008     6
PRO1     DEPARTMENT2          Task3     01/15/2008     15
Note: The rows having blank dates indicate remaining work for that task
Based on user requirements, I have created a OLAP model as follows
Dimensions:
1. All Projects-->Projects
2. All Department-->Department
3. All Tasks     --> Tasks
4. Year-->Month-->Day
Measures:
1. Total units of work (Irrespective of date)
2. Cumulative units of work completed (Based on the date)
If someone has worked on similar models before, I would be thankful if they can help me with
1) An aggregation plan for these measures. (Basically, for my first measure, I would want to get a cumulative total across my time dimension, and for my other measure, I would like to see the total units, whatever date I pick, for example, for Dep1, Task1, this measure should show 27 on 01/01/08 and also on 01/21/08 and also when I roll up and look at year 2008, I still need 27 in this column)
2) Is it ok to apply Skip level aggregation to this type of calculations, or would that result in some problems?
Any and All suggestions to implement this are welcome.
Thanks,
Bharat

Hi,
Can you build time dimension to include as many years as your application needs (2000 to 2025 say)? Then you can simplify the model a lot by defaulting the records with remaining units -- the ones with no date -- with the last date in your time dimension (31-DEC-2025). So in a sense, you're loading them as if they'll be complete on 31-DEC-2025.
Also you should have a grand total level (ALL_YEARS say) along time dimension which contains a single member which includes all the years.
Cube with 3 dimensions: Projects, Dept, Task, Time and 1 Fact: Units
You can use calculated measures to get the results you want
1. Total units of work (Irrespective of date) ... reference top most member. Will include all -- completed and incomplete units of work.
Expression: cube1_units(time 'ALL_YEARS_1').. or use olap dml function to get the last member programatically if desired... Alternate Expression: cube1_units(time limit(time to time_levelrel eq 'ALL_YEARS')).
2. Cumulative units of work completed (Based on the date)
2a: Create formula/measure which is a regular Cumulative summation of Units .... Note: you need a Period-To-Date calculation set to sum up all peers under ancestor at level: ALL_YEARS (instead of year)
This will include all completed units until the day in question. Since incomplete units are on the last day, they will not count.. You may need to add a special check for the last day.
Use another formula to reference 2a appropriately across all levels of time...
Formula for Measure #2: if time_levelrel eq 'DAY' then 2a else 2a(time statlast(limit(time to bottomdescendants using time_parentrel time(time time))))
For higher levels of time (above day), you should reference the Cumulative units of work for the last day of the relevant period. E.g. To get completed units of work for October 2011, you need to reference the value of 2a. for last day of the Month: 31-Oct-2011.
HTH
Shankar

OBIEE 10g - Ragged & Skip Level Hierarchy

Hi Frnds,
I'm aware of the fact that OBIEE 11g supports Ragged & Skip Level Hierarchy. But I'm looking for some heads up while implementing the same on OBIEE 10g using Oracle DB as source. I have done this before for Essbase Data Source but now waiting for my Oracle dataset for design.
Has anyone actually implemented in Real Time Project? Pls share your challenges like:
- Dimensional Hierarchies Challenges
- Drill Down Challenges
- Report Challenges
Thanks,
Deepak
Edited by: Deepak Gupta on Aug 11, 2011 5:18 AM

Deepak,
10g does not handle the idea of Skip hierarchies and the ragged hierarchies definitely has its limitations.
We've implemented several projects using Essbase and SAP BW for Oracle BI 10g. The biggest issue is that in Answers creates a new column for each drill down selection when attempting to navigate down a hierarchy. Though this is klugy it does work and provides the data the user is looking for. It is however, not aesthetically please when compared to other tools or now Oracle BI 11g which satisfies this issue with a native drill-down tree folder structure.
My opinion and advice would be to upgrade to 11g as soon as possible to enjoy these new features.

CSS Level 2 Support for RGB Hex Abbreviation

when creating a style sheet during the tutorial in
Flash 8: Training from the Source, i abbreviated my hex
colors as usual when i have repeating pairs (in this particular
case #999 instead of #999999) and the publised Flash page would not
display the correct color. it displayed black text instead of gray.
after changing the #999 to the full #999999, the republished
Flash page displayed the page correctly. I understand from the book
Flash 8 does not support level 2 CSS, which includes more than my
simple abbreviation issue.
when do you (Adobe Flash Team) expect to incorporate CSS
level 2 support into the product? is it supported by Flex 2, as I
am not too familiar with that platform yet?
thank you,

Hi Mike,
OHJ uses the ICE Browser, which we license from a company named ICESoft. It generally compares favorably with other Java-based browsers, although it is not as complete as a native browser such as IE or Firefox.
There is a list of what is and is not supported in CSS:
http://www.icesoft.com/developer_guides/icebrowser/htmlguide/featuresappendix3.html#86328
We recently finally resolved the licensing issues that were holding us back from releasing a version of OHJ with JavaScript support. The current versions don't support JavaScript, but our next major release will.
Depending on your needs, we also have OHW, which is a server based help system, that uses the client's native browser.
Regards,
Jeffrey Stephenson
Oracle

Release 600, Level 11 (support pack SAPKGPAD11) vs Release 604, Level 03 (s

Hi,
We are moving into the SAP ECC enviroment and need to understand the difference between the 2 Support Packs Release 600, Level 11 (support pack SAPKGPAD11) vs Release 604, Level 03 (support pack SAPK-60403INEAAPPL).
Can anyone give us an indication in terms of functionality what we should be looking out for? During the testing we already came across and issue regarding double invoicing but this was fixed with a OSS note.
From a coding, functionality, intergration and process perspective,how do we know what the differences are? Is there a document that lists these difference as a quick comparison between the two releases.
Thanks in advance

Hi,
There is lot of difference btween 2. ECC System with EHP4 (Release 604 Level 3), ECC package will be on 604 release and level represents the support pack level of 604 release. If your system is on this level then it means that your system is with Enhancement packages but if your ECC components are on release 600 then it is without Enhancement packages.
Enhancement packages has been delivered a lot of new things like New GL etc. More information for what extra features ECC 6.0 with EHP4 has: can be checked on http://service.sap.com/erp-ehp.
To take your system from 600 release to 604 release requires a lot of effort because you have to upgrade your system to bring at this release.
Thanks
Sunny

Value based hierarchies, Skip Level Hierarchies

Hello,
I need to create hierarchy based on column value , Please give me some details on implementing value based hierarchies and skip level hierarchies in obiee 10.1.3.
Thank you

With 10.3 i do not think we have a inbuilt solution to build value based hierarchies, you have to flatten the hierarchy and build a level based hierarchy.
OBIEE 11g has value based hierarchies feature.
refer this one for 11g.
http://sandybi.wordpress.com/2010/08/17/hierarchies-in-obiee-11g-part-1/
- Madan
Edited by: Madan Thota on Sep 14, 2010 11:15 AM

Poor performance when using skip-level hierarchies

Hi there,
currently we have big performance issues when drilling in a skip-level hierarchy (each drill takes around 10 seconds).
OBIEE is producing 4 physical SQL statements when drilling f.e. into the 4th level (for each level one SQL statement). The statements runs in parallel and are pretty fast (the database doesn't need more than 0,5 seconds to produce the result), but ... and here we have probably somewhere a problem ... putting all the 4 results together in OBIEE takes another 8 seconds.
This are not big datasets the database is returning - around 5-20 records for each select statement.
The question is: why does it take so long to put the data together on the server? Do we have to reconfigure some parameters to make it faster?
Please guide.
Regards,
Rafael

If you really and exclusively want to have "OBIEE can handle such queries" - i.e. not touch the database, then you had best put a clever caching strategy in place.
First angle of attack should be the database itself though. Best sit down with a data architect and/or your DBA to find the best setup possible physically and then when you've optimized that (with regard to the kind of queries emitted against it) you can move up to the OBIS. Always try t fix the issue as close to the source as possible.

Ragged Hierarchy and Skip Level Hierarchy

Hi all,
I am confused with ragged and skip level hierarchy, as i read some documents related to obiee 11g.
Will you please explain with an example the difference between ragged hierarchy and skip level hierarchy and also when to use these hierarchies?
regards
chandra kanth.

Chandra Kanth,
Hope this helps you
http://blogs.simba.com/.a/6a00e3932f172e88340133f4d758b5970b-800wi
Thanks,
Saichand.v

OBIEE Essbase skip-level hierarchy

Is it possible to setup OBIEE and Essbase to be able to model skip-level hierarchy? It is obvious with connection to the relational database. How the essbase should designed and populated with data to faciliate this type of hierarchy?

Refer this http://www.oracle.com/technetwork/middleware/bi-enterprise-edition/overview/obiee-essbase-modeling-guide-130897.pdf for Modeling. And for any Essbase releated question post it in Essbase forum Essbase

ROLAP skip level dimension support - CWM2?

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