Usage of line item dimension - design or run time?

Hi,
Can anyone please tell me at which stage a line item dimension is considered - at design time or after data load, once queries are run and performance degenerates?
I have read many posts and blogs about line item dimension and high cardinality, but I would require more information on when a line item dimension comes into play.
If we can decide at design time, then how is it done without data being loaded?
At which instances will the dimension table size exceed the fact table's size?
Please explain the above 2 points with a clear example, including the DIM ID and SID table access, and the ratio calculation for line item dimension consideration.
Thanks in advance.

Hello Aparajitha,
I agree with Suhas on point of consideration of LID . It would be good enough to consider a Dimension as LID in the Cube during design, it will be fruitful for the performance point of view. There is no point in saving the LID for future purpose if you have less than 13 Dimension in the Cube. It is going to save a extra join in connecting the relevant data.
If the total Dimension exceeds 13 or more (during design) , then you no option but include the related Char IO together in a one dimension.Here you cannot make a LID .
During the run phase, if the Dim table is more than 20 % of Fact Table, then for the sake of performance you have to go for the LID.In that case you will have the overhead of managing data (backup, delete & restore) .
On your specific questions :
"If we can decide at design time, then how is it done without data being loaded "
Technically same as you do during run-- Goto Dimension -- Right click --Properties -- and Check LID.
Logically -- Depending upon the Business meaning, which char has max unique values you can go with as LID.
"At which instances will the dimension table size exceed the fact table's size "
Frankly I haven't come across that.. ... Fact table is the center table and always will be the huge table in comparison to Dim table . Dim table cannot exceed the Fact Table ....!
Yes if the size of Dim Table is more than 20% of Fact table ( ratio of Dim Table to Fact Table) , then we have to select between the LID or High Cardanility.
Gurus..Please correct if anything is wrong ..!
Regards
YN

Similar Messages

InfoCube Design for Variable data - Use of Line Item Dimensions

I have an infoprovider based on billing conditions which we have extended the extractor structure for 2LIS13_VDKON and we now have a requirement to add Customer fields such as Customer Purchase Order Number and Contract Number. These fields are obviously highly variable. I have added to them to the reporting DSO and now need advice on what is the best way to add these types of fields as reportable dimensions to the infocube so as to not impact performance? I currently have 9 dimensions with multiple charachteristics and a time dimension. Should I just create a line item dimension for Purchase Order? Problem is I have 8 other line item dimensions to add which are customer specific reporting fields that we capture on the sales order and wish to report on. I know there is a limit of 16 dimensions and I am also concerned about performance.
Any advice is greatly appreciated
Lee Lewis

Hi,
To make sure that the infocube you have created should not have any performance issue: Please do the following
Go to RSRV > All elementary tests-> Database---> database information about infoprovider tables
Upon clicking on database information about infoprovider tables, on the right hand side, in the parameter enter your infocube name and execute and see the log: ( log will automatically popping up once you are done with execution )
There see the database infomation about infoprovider:
This log wil make you to understand how well you have designed your infocube and make sure that each (f ) table corresponding to each dimension will not exceed 20 % of the infocube size.
You create dimensions of infocubes in a such a way ( whether line item or normal dimension ) so that any of the dimensional F table will not exceed 20 % of the infocube size.
Actually this will give us the information of the size of the data of particular dimension and there by if any particular dimension is exceeding the 20 % of the infocube size, then you need to create line item dimension for the characteristics existing in that dimension .
After creating again, test it and see whether any of the dimension table exceeding 20% infocube size .
Repeat this process until you see all dim F tables less than 20 % of the info cube table size
This will negate any performance issues arise in reporting
Edited by: S Simran on Nov 6, 2009 10:11 AM

Line Item dimension

Hi friends!
The auditor suggest us "flag the line item option in the dimensions with high cardinality, ie: document number, material number"
In my cubes have 0customer in dimension C toghether with other other characteristics, and 0material in dimension M together to other characteristics..
a) is the auditor suggest ok?
b) do I need mark this dimension as 'line item' in my cubes if the dimension M or C has more than one char?
c) do I need change the arquitecture in my cube and leave 0material alone in dimension M and in dim C only the char 0customer?
Thanks in advance!

Regarding High Cardinality :
If the values in the table are distinct - where the uniqueness of the values is high - a Bitmap index is preferred since the unique values are high...
As for Line item dimension - in a Line Item dimension - only one characteristic is allowed in a line item dimension and the SIDs will get stored directly in the Fact Table and the additional lookup of SIDs with the master data is avoided...
a) is the auditor suggest ok?
I would say that high cardinality is a better option as opposed to line item dimension . For Document Number - a Line item Dimension is preferred since Document number is typically used in reporting but not much on searches for the same ..
Also this is with the information you have given - it could also be that there is some more information to it that Line Item Dimensions were suggested ...
b) do I need mark this dimension as 'line item' in my cubes if the dimension M or C has more than one char?
You can mark a dimension as Line Item only if there is one characteristic
c) do I need change the arquitecture in my cube and leave 0material alone in dimension M and in dim C only the char 0customer?
Keep document number in line item - run the report to analyze the sizes of fact versus dimensions and then rearrange the characteristics to get better ratios instead of making Material and Customer as Line item Dimensions...
Also Material and Customer are usually viewed along with their Nav Attribtes - making them as Line Item will not give you much savings in terms of performance
Edited by: Arun Varadarajan on Mar 25, 2010 1:13 AM

How can i decide candidates for line item dimension?

1Q): we have many infocubes out of all these infocubes, i have to decide which infocubes are the candidates for lineitem dimension? How to do it? Please tell me the technical specs how to do the analysis to find out the candidates for line item dimension?
2Q): if i have the small dimension can i combine all these dimension in to one dimension? what is the benefit of doing this? how to find out which dimensions are small?
Pizzaman i like to hear from you on this topic. Thanks to SDN Community. i appreciate your help. Again Thank you.

The process of figuring out what you might want to create as a line item dimension can vary a bit, it can depend a lot on your exisitng level of domain expertise (how well do you know the data in question). If you are familiar with the data, I would recommend you just take an initial guess at what you believe could be line item dimensions. If you are not familiar witht the data, you might want to examine the source more to understand the cardinality of different characteristics and identify any relationships between characteristics.
I really encourage people to just go ahead and model it and load some data and review, rather than agonizing over developing the theoretically perfect model on paper before they start. You learn a lot more that way.
Any of the SAP rules of thumb, are just that, general rules, not a pronouncement from God. There are always extenuating or unique circumstances that might warrant disregarding the rule, e.g. if the InfoCube will never become very large, maybe some of the concerns just are not worth your effort.
With every release of the Oracle (and the other DBs too)Oracle keeps getting better at data warehousing and star schemas. Oracle 10i is supposed to have made handling bitmap indices much more efficient, which is on of the factors influencing the decision to create a line item dimension.
There are other threads on SDN on line item dims that provide more technical detail and can help answer you first question
As far as 2Q - generally, it's better to have several small dimensions than one larger dimension. But having said that, combining a few very small dimensions into another slightly larger (but still small) dimension is a good idea. It keeps the number of table joins down which will improve query performance. You would do this with characterisitcs that have very few values, e.g. yes/no indicators.
e.g.
You have 8 characteristics that all of which have only two values. You put them in one dimension, and the max size of the dimension table is still only 2x2x2x2x2x2x2x2 or 256 rows. If you had these characteristics in other much larger dimensions, it's not hard to see it causing those dimensions to double, perhaps creating hundreds of thousands of dimension table rows to be created.
For more - read <a href="http://www.kimballgroup.com/html/designtipsPDF/DesignTips2003/KimballDT48DeClutter.pdf">Ralph Kimball Design Tip 48 - Junk Dimensions</a>

Line item dimensions and cardinality?

hi all,
how to identify nor use the cardinality relationship as well as the line item dimension?
can anyone explain me about it. since i am trying to create an multi provider which enables to fetch data from 3 ods.
regds
Hari Chintu

Hi,
Below is some useful information on Line item dimension and high cardinality.
These concepts hold good for Cube design only, coming to ODS, these dont help you. As ODS is nothin but a flat structure, we do not have the facility of Star schema. Reporting on ODS can lead to performance issues, it is better to load data from ODS into Cube and then have a multiprovider on them instead of having it on ODS.
Hope this helps.
Regards,
Kalyan
Use
When compared to a fact table, dimensions ideally have a small cardinality. However, there is an exception to this rule. For example, there are InfoCubes in which a characteristic document is used, in which case almost every entry in the fact table is assigned to a different document. This means that the dimension (or the associated dimension table) has almost as many entries as the fact table itself. We refer here to a degenerated dimension. In BW 2.0, this was also known as a line item dimension, in which case the characteristic responsible for the high cardinality was seen as a line item. Generally, relational and multi-dimensional database systems have problems to efficiently process such dimensions. You can use the indicators line item and high cardinality to execute the following optimizations:
       1.      Line item: This means the dimension contains precisely one characteristic. This means that the system does not create a dimension table. Instead, the SID table of the characteristic takes on the role of dimension table. Removing the dimension table has the following advantages:
        When loading transaction data, no IDs are generated for the entries in the dimension table. This number range operation can compromise performance precisely in the case where a degenerated dimension is involved.
        A table- having a very large cardinality- is removed from the star schema. As a result, the SQL-based queries are simpler. In many cases, the database optimizer can choose better execution plans.
Nevertheless, it also has a disadvantage: A dimension marked as a line item cannot subsequently include additional characteristics. This is only possible with normal dimensions.
       2.      High cardinality: This means that the dimension is to have a large number of instances (that is, a high cardinality). This information is used to carry out optimizations on a physical level in depending on the database platform. Different index types are used than is normally the case. A general rule is that a dimension has a high cardinality when the number of dimension entries is at least 20% of the fact table entries. If you are unsure, do not select a dimension having high cardinality.
Note: In SAP BW 3.0, the term line item dimension from SAP BW 2.0 must a) have precisely one characteristic and b) this characteristic must have a high cardinality. Before, the term line item dimension was often only associated with a). Hence the inclusion of this property in the above. Be aware that a line item dimension has a different meaning now than in SAP BW2.0.
However, we recommend that you use ODS objects, where possible, instead of InfoCubes for line items. See Creating ODS Objects.
Activities
When creating dimensions in the InfoCube maintenance, flag the relevant dimension as a Line Item/ having High Cardinality.

Regarding line item dimension

Hi all,
what are the necessary prerequisities will u take regarding line item dimension.
for eg., for sd cubes we r using sales doc no., i.obj as a line item dimension? why can't the other i.obj?
plz explain me clearly?
Thanks & Regards,
V.Vijay.

HI,
Line Item and High Cardinality
When compared to a fact table, dimensions ideally have a small cardinality. However, there is an exception to this rule. For example, there are InfoCubes in which a characteristic document is used, in which case almost every entry in the fact table is assigned to a different document. This means that the dimension (or the associated dimension table) has almost as many entries as the fact table itself. We refer here to a degenerated dimension. In BW 2.0, this was also known as a line item dimension, in which case the characteristic responsible for the high cardinality was seen as a line item. Generally, relational and multi-dimensional database systems have problems to efficiently process such dimensions. You can use the indicators line item and high cardinality to execute the following optimizations:
Line Item Dimensions
Line item: This means the dimension contains precisely one characteristic. This means that the system does not create a dimension table. Instead, the SID table of the characteristic takes on the role of dimension table. Removing the dimension table has the following advantages:
¡ When loading transaction data, no IDs are generated for the entries in the dimension table. This number range operation can compromise performance precisely in the case where a degenerated dimension is involved.
¡ A table- having a very large cardinality- is removed from the star schema. As a result, the SQL-based queries are simpler. In many cases, the database optimizer can choose better execution plans.
Nevertheless, it also has a disadvantage: A dimension marked as a line item cannot subsequently include additional characteristics. This is only possible with normal dimensions.
High Cardinality
If your dim table size exceeds the 20% of your fact table then you can say it as high cardinality, for ex: your fact table contains 100 records and your customer dimension contains 25 records means this dim is with high cardinality. you can check with your client for the expected records for those dimensions or for the info objects which you define in one dimension. to know the sizes of the dimension tables and fact tables you can runa a program in SE37 SAP_INFOCUBE_DESIGNS, it displays all your info cubes fact and dimension tables with sizes, if any dimension exceeds the more than 10% to 20% it will be in RED.
It means that the dimension is to have a large number of instances (that is, a high cardinality). This information is used to carry out optimizations on a physical level in depending on the database platform. Different index types are used than is normally the case. A general rule is that a dimension has a high cardinality when the number of dimension entries is at least 20% of the fact table entries. If you are unsure, do not select a dimension having high cardinality.
http://help.sap.com/saphelp_nw04/helpdata/en/b2/fbb859c64611d295dd00a0c929b3c3/frameset.htm
http://help.sap.com/saphelp_nw70/helpdata/en/a7/d50f395fc8cb7fe10000000a11402f/frameset.htm
http://help.sap.com/saphelp_nw04/helpdata/en/5c/d14d3c306f090ae10000000a11405a/frameset.htm
Note: In SAP BW 3.0, the term line item dimension from SAP BW 2.0 must a) have precisely one characteristic and b) this characteristic must have a high cardinality. Before, the term line item dimension was often only associated with a). Hence the inclusion of this property in the above. Be aware that a line item dimension has a different meaning now than in SAP BW2.0.
SAP recommends that you use ODS objects, where possible, instead of InfoCubes for line items.
Tarak

What is line item dimension and cardinality in BI 7.0

Can u plz suggest me what is line item dimension and cardinality in BI 7.0..
Thanks in advance.
Venkat

Hi Babu
Line item: This means the dimension contains precisely one characteristic. This means that the system does not create a dimension table. Instead, the SID table of the characteristic takes on the role of dimension table. Removing the dimension table has the following advantages:
¡ When loading transaction data, no IDs are generated for the entries in the dimension table. This number range operation can compromise performance precisely in the case where a degenerated dimension is involved.
¡ A table- having a very large cardinality- is removed from the star schema. As a result, the SQL-based queries are simpler. In many cases, the database optimizer can choose better execution plans.
Nevertheless, it also has a disadvantage: A dimension marked as a line item cannot subsequently include additional characteristics. This is only possible with normal dimensions.
Note: In SAP BW 3.0, the term line item dimension from SAP BW 2.0 must a) have precisely one characteristic and b) this characteristic must have a high cardinality. Before, the term line item dimension was often only associated with a). Hence the inclusion of this property in the above. Be aware that a line item dimension has a different meaning now than in SAP BW2.0.
SAP recommends that you use ODS objects, where possible, instead of InfoCubes for line items.
Hope this helps.
Plz check these links:
SAP Help:
http://help.sap.com/saphelp_nw04s/helpdata/en/a7/d50f395fc8cb7fe10000000a11402f/frameset.htm
Thanks & Regards
Reward if helped
Edited by: Noor Ahmed khan on Aug 5, 2008 2:36 PM

Loaded Cube Modification in BI 7.0 (Line item Dimension)

Hi
We need to modify the cube 0CA_C11, as in one of the dimension it conatian huge data , we planed to make that line item dimension , by creating new dimension and move some Object to the new dimension.
in BI 7.0 is there any option that we can can create a new dimension with out deleting the data.
We tried in Remodling in that there is no option of creating new dimension
kindly suggest me
many many thankz

Hi
We need to modify the cube 0CA_C11, as in one of the dimension it conatian huge data , we planed to make that line item dimension , by creating new dimension and move some Object to the new dimension.
in BI 7.0 is there any option that we can can create a new dimension with out deleting the data.
We tried in Remodling in that there is no option of creating new dimension
kindly suggest me
many many thankz

Line item dimension wont insert sid values in infoobject sid table

Hi all,
I have a strange problem, whenever I load data into a cube which has a line item dimension on 0customer without first loading the master data I am getting inconsistency in RSRV saying that no corresponding DIMid exists in sid table.
So there are Dimids in the fact table but the dimension table, which is same as the sid table in the the case of line item dimension, doesnt have them.
Can someone explain me why is this happening? I thought if a characteristic value doesnt exist in the master data but comes in through the transaction data it inserts the same in the sid table.
Is there a different rule for line item dimensions? Can someone point me to some OSS or documentation?
thanks

Thanks all..
To clear up a few questions:
1. What I mean by "So there are Dimids in the fact table but the dimension table, which is same as the sid table in the the case of line item dimension, doesnt have them" is:
the line item dimension table /bic/D<cubename>9 which is really a view on the sid table for characteristic /bic/s<ch. name> does have all the sid values (or all the dim values) as the fact table.
So fact table has more entries for that dimension than the sid table.
2. Yes we are facing reporting errors where we cannot drill down by that infoobject and LISTCUBE doesnt show us any cube data when that characteristic is chosen for display.
3. I have checked notes where it seems to be a RSRV bug but in our case it doesnt seem to be as observed in the actual table mentioned in #1
Now it is apparent that I am right both from help.sap.com link and what I am observing that for line item dimensions master data HAS TO BE LOADED FIRST for the characteristics used as a line item.

DB Statistics on Line item dimension

Hello,
We have a new cube with WBS element as line item dimension. the cube has around 600,000 records in fact table. The problem is the DB statistics is stuck at sampling the master data table for WBS element.
In all our cubes WBS element is always a line item and we do stats for these cubes every week, so why is this taking long. I thought that stats is per table and not per infocube? Correct me if I am wrong.
I would also like to if performing stats from the backend like DB13 jobs or DB20 or ORACLE DB is better and sufficient or the Cube Stats is also needed.
Thanks

Just saw this - in 3.1 SP22 - OSS Note <a href="https://websmp201.sap-ag.de/~form/sapnet?_FRAME=CONTAINER&_OBJECT=012003146900000348972005">862176</a> indicates that statistics collection on all dependent tables for a cube from the performance tab or as a result of automation settings should NOT be ocurring - just collection on F fact and dimension tables.
This note provides a fix. This should speed up statistics collection if you use these methods.

Line Item Dimension in a Infocube

Hi,
What is a Line Item Dimension in BI and
How can/based on What factors we can decide declare a Infoobject as a Line Item dimension in Cube
How to measure size of the fact table
Thanks

Hi,
For working out the largest fact tables:
transaction DB02 -> space statistics -> top n largest tables.
If this does not help, your DB administrator should be able to extract the information using SQL.
Also you can use tcode ST14 -> BW Evaluation: performance analysis of BW objects.
Rgds,
Colum

Line item dimensions

hi..
wat is line item dimensions nd cardinal heights???
regards
deepa

Hi Deepa,
Line Item Dimension:
When your dimension table becomes large (>10% of the fact table) then you can make the dimension a "line-item" dimension. The constraint is that the dimension should have only 1 characteristic. By making the dimension as line item the SID values are directly used instead of the Dim ids and the query performance is better.
The disadvantage is that once you make the dimension line -item you cannot add another characteristic to that dimension and you cannot remove the line -item checkmark without deleting the cube data.
http://help.sap.com/saphelp_nw04/helpdata/en/a7/d50f395fc8cb7fe10000000a11402f/frameset.htm
Multi Dimensional modelling will include fact table in center with Dimension tables around it. Overall system performance is greatly affected and dependent on the size of these dimension tables in respect to the fact table. SAP recommends that size of dimension table should be 20% of the size of fact table. In case if this size is more than 40% dimension should be defined high cardinal ( should be supported by database) If dimension tables are more than 40% the dimension should be defined as line item. When dimension is defined as line item, Dim ID in the fact table is replaced with the SID ID, Only one characteristic will be defined in that dimension. This results in improved performace.
Here is how it will work
Fact table
Dim ID1 DIM ID2 DIM ID3 AMOUNT QTY
Dimension Table 1
Sid1 DimID1
Dimension Table 2
Sid 4 Dim ID 2
Dimension Table 3
Sid6 Dim ID 3
Cosidering that Dim1 is too big, We can define Sid 1 in Line Item Dimension and Dim ID 1 is replaced by Sid 1 so fact table will look like this
Sid 1 Dim2 Dim3 Amount Qty
Compounding Attribute is superior object to define characteristic, for example
Plant A manufactures TV
Plant B manufacture TV
The only way to differentiate product can be TV and Plant A
Also,
Cost center 100 can be in Controlling Area A and
Controlling Area B can also have cost center 200,
So Cost center is compounded with CO Area to uniquely identify that line.
Just check this thread line item dimension
Cardinality defines the numeric relationships between occurrences of the entities on either end of the relationship line.
Check this link:
http://www.datamodel.org/DataModelCardinality.html
For cubes -> High Cardinality means that this dimension contains a large number of characteristic values. This information is used in accordance with the individual database platform in order to optimize performance. For example, an index type other than the standard may be used. Generally a dimension is perceived to have high cardinality when the dimension is at least 20% the size of the fact tables in terms of the number of entries each contain. Avoid marking a dimension as having high cardinality if you are in any doubt.
Also refer the below link for Line Item Dim and High Cardinality.
http://help.sap.com/saphelp_nw04/helpdata/en/a7/d50f395fc8cb7fe10000000a11402f/frameset.htm
Check this explanation by pizzman:
Re: High cardinality (CARDHeight) vs Line item
Refer these links on line-item and cardinality:
Line Item Dimension
Re: Line Item Dimension
Cardinality
Re: High Cardinality Flag
****Assign Points If Helpful****
Regards,
Ravikanth

Line item dimension issue

Hi,
      I am on development system and want to know the fact and dimension % as I need to create line item dimesion.
One solution is executing program SAP_INFOCUBE_DESIGN.
      But if I want to use this same program in Production system, it will take a lot of time and will engage resources......
      Kindly suggest me as to how to find out which dimension should be made a line item dimension?
Thanks,
Sonu

Hi,
Use RSRV.
Execute RSTRV and here you have the option of single cubes.
This takes the ourput from the same tables where the SAP_INFOCUBE_DESIGNS takes.
All Elementary Tests -> Database -> Database Information about InfoProvider Tables.
Give your infocube name here and execute.
It gives you a good detailed output.
Thanks
Ajeet

How to know what were line item dimensions

Dear SDN,
How to know what were made line item dimensions.
Thankyou.

Rahul,
Go to the edit mode of your info cube and then check out your dimensions, there if the line item dimension check box is checked then it means that, that particular dimension is a Line item dimension.
Regards,
Gattu

Line item dimension,partitioning IN BW7.0

HOW TO MAKE A CHARACTERISTIC AS LINE ITEM DIMENSION.
STEPS FOR CREATING PARTITIONING IN CUBE
Edited by: TSUCHITRA on Jul 28, 2010 12:08 PM
Please search the forum before posting a new thread
Edited by: Pravender on Jul 28, 2010 7:53 PM

Have you tried the help files?
Partitioning here
http://help.sap.com/saphelp_nw04/helpdata/en/33/dc2038aa3bcd23e10000009b38f8cf/frameset.htm
Line item dimension here
http://help.sap.com/saphelp_nw04/helpdata/en/a7/d50f395fc8cb7fe10000000a11402f/content.htm
Should these excellent help files not help you - please don;t hesitate in coming back with more specific questions

Usage of line item dimension - design or run time?

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