Create repository from database model- snowflake facts and dimension joins

I am working on a project that has a database model similar to the image in the link below.
There are other few tables around it, but this generally represent the spine or major database model. This is not exactly a snowflake schema as there are no intrinsic hierarchy in the dimension tables. As you can see dim2 and dim4 has one to many relationship with dim3. there are joins between the fact tables as well.
From some blogs and forum threads, I found out that I can create one fact/dimension table by joining many fact/dimension tables. Is this a right approach? Any thoughts on this model please?
Thanks,
Rakesh
ps: I am using Windows XP Pro and OBIEE 10.1.4.3.1 and right now analyzing the data to create a repository.

Hi Rakesh,
As above post says you combine all fact tables into single fact table with other dimension tables so it would become a simple start schema .Go throught these blogs for further information .
http://forums.oracle.com/forums/thread.jspa?threadID=2124061&tstart=0
http://www.obinotes.com/2010/08/joins-within-logical-table-sources-in.html#comment-form
Hope it helps you.Seems your new to forum you sud follow these rules http://forums.oracle.com/forums/ann.jspa?annID=939
By,
KK

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Facts and dimensions joins

Hi,
Can we use three fact tables in rpd and not join them? We have three facts and four dimensions. All the four are common dimensions to the three fact tables. So in the physical joins can we just join the facts to the dimensions? will it be accepatble if we do not have a join between fact tables. Is it necessary that all the tables (fact and dimensions) need to be joined to some tabler? Can we leave the joins between the facts which are not necessary? Please advice.

We do not do joins between fact tables, the joins between facts will be happened through dimensions (conformed dimensions).
In your case the 4 dimension will act as an conformed one.
Is it necessary that all the tables (fact and dimensions) need to be joined to some tabler? You cannot have a table in BMM which is not joined to any other table.
Can we leave the joins between the facts which are not necessary?Yes, Dim1 - fact1 -Dim 2 in this fact 1 is connected with Dim1, Dim2 and there is no relationship for fact1 with Dim3 so we don't join it.
Dim1,Dim2,Dim3 is joined with fact2 in this case Dim 1 and Dim2 will act as conformed dimesion between fact1 and fact2, where as dim3 will be a non conformed dimesion.
Thanks,
Vino

Issue with Fact and Dimension join

Hello,
I have two Facts F1 & F2 and two Dimensions D1 & D2.
in my schema, D1 is the common dimension between F1 & F2 and D2 is joined to F2 only.
so when I am trying to get one record from each of D1, D2, F1 & F2 the query is not getting generated for D2 & F2. It is only creating a query like " select a1,a2, a3 from F1,D1,F2 where D1.a2=F1.a1 and D1.a2=F2.a3".
Need some suggestion where i am wrong that OBIEE is not creating query for D2 & F2 join.
Thanks,
-Shub

Discussed multiple times Business Intelligence Suite Enterprise Edition .

Join multiple facts and dimensions for reporting issue

Hi,
I have a report requirements and need to use multiple fact tables and unconformed dimensions as described below
Fact table: F1,F2,F3
Dimensions tables: D1.....D9
F1:(joined to) D1,D2,D3,D4
F2::(joined to)D1,D2,D5,D6
F3::(joined to)D1,D2,D7,D8
D7::(joined to)D9,D8 (dimension D7 joined to two other dimensions D9 and D8
I'm trying to use columns from almost all the fact and dimension tables but getting "Unable to navigate requested expression. Please fix the metadata consistency warnings."
Repository is consistent and no errors and warnings.
How can I configure the repository to develop reports using all fact tables and dimensions?
Appreciate for your help.
Thanks
Jay.

You can find the same issue in
Logic of queries in OBIEE
or
Connection between 2 fact tables
Follow the link
http://there-n-back-again.blogspot.com/2009/04/oracle-analytics-how-to-report-over-non.html
Put 'All' or 'Total' at levels for dim_xxx for those facts you need in your report from facta and factb
Regards
Nicolae

Unable to Create Fact and Dimension tables from the Tools menu in EIS conso

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What I should do If I move fact and dimension tables from one server to other server

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Best practice when FACT and DIMENSION table are the same

Hi,
In my physical model I have some tables that are both fact and dimension table, i.e. in the BMM they are of course separated into Fact and Dim source (2 different units) and it works fine. But I can see that there will be trouble when having more fact tables and I e.g. have a Period dimension pointing to all the different fact tables (different sources).
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Table as fact and dimension

Hi,
Can one table act as a fact in one subject area and act as a dimension in another subject area? Thanks.

Hi
I confirm Stijn Gabriels' post.
You don't have to do an alias in your physical table, otherwise the request will generate an alias in SQL for nothing ! However, in your logical layer, you will create 2 logical table : one for the fact, one for dimension. Both of them will have the same source : your unique physical table.
Let's take an example : suppose you have only 2 table in your datawarehouse : 1 fact table with degenerate dimension attributes (so a table with fact and dimension data), we'll call it "revenue", and 1 dimension table for... "Time", for example. We'll call it"Time"
Your conceptual (on paper) is a star schema with 1 fact table (revenue_fact), and 2 dimension table (time, and revenue_carac).
In your OBIEE physical layer :
- you import the 2 tables "revenue" and "time" from your database.
- you link "revenue" with "time"
In your OBIEE logical layer :
- you create a logical table called "Dim Time", based on the "Time" physical table and you do what you want with it (hierarchy...)
- you create a logical table called "Dim Revenue Carac", based on the "revenue" physical table, and you do what you want with attributes
- you create a logical table called "Fact revenue", based on the "revenue" physical table, and you do you what you want with measures and aggregation
- you link the 2 logical dimension table with the logical fact table
And that's all. Now, let's see which kind of SQL OBIEE will generate if you want to display the measure "revenue" with the attribute "revenue_carac" and the attribute "year".
Select Sum(R.revenue_measure) , R.revenue_carac , T.year
From revenue R , time T
Where R.time_id = T.id
Group by R.revenue_carac , T.year
If you set alias in your physical layer, the request will be that (and you don't want it) :
Select Sum(R1.revenue_measure) , R2.revenue_carac , T.year
From revenue R1, revenue R2 , time T
Where R1.time_id = T.id
And R1.id = R2.id
Group by R2.revenue_carac , T.year
same results, but useless join between the same physical table

Fact and dimension table partition

My team is implementing new data-warehouse. I would like to know that when should we plan to do partition of fact and dimension table, before data comes in or after?

Hi,
It is recommended to partition Fact table (Where we will have huge data). Automate the partition so that each day it will create a new partition to hold latest data (Split the previous partition into 2). Best practice is to create partition on transaction
timestamps so load the incremental data into a empty table called (Table_IN) and then Switch that data into main table (Table). Make sure your tables (Table and Table_IN) should be on one file group.
Refer below content for detailed info
Designing and Administrating Partitions in SQL Server 2012
A popular method of better managing large and active tables and indexes is the use of partitioning. Partitioning is a feature for segregating I/O workload within
SQL Server database so that I/O can be better balanced against available I/O subsystems while providing better user response time, lower I/O latency, and faster backups and recovery. By partitioning tables and indexes across multiple filegroups, data retrieval
and management is much quicker because only subsets of the data are used, meanwhile ensuring that the integrity of the database as a whole remains intact.
Tip
Partitioning is typically used for administrative or certain I/O performance scenarios. However, partitioning can also speed up some queries by enabling
lock escalation to a single partition, rather than to an entire table. You must allow lock escalation to move up to the partition level by setting it with either the Lock Escalation option of Database Options page in SSMS or by using the LOCK_ESCALATION option
of the ALTER TABLE statement.
After a table or index is partitioned, data is stored horizontally across multiple filegroups, so groups of data are mapped to individual partitions. Typical
scenarios for partitioning include large tables that become very difficult to manage, tables that are suffering performance degradation because of excessive I/O or blocking locks, table-centric maintenance processes that exceed the available time for maintenance,
and moving historical data from the active portion of a table to a partition with less activity.
Partitioning tables and indexes warrants a bit of planning before putting them into production. The usual approach to partitioning a table or index follows these
steps:
1. Create
the filegroup(s) and file(s) used to hold the partitions defined by the partitioning scheme.
2. Create
a partition function to map the rows of the table or index to specific partitions based on the values in a specified column. A very common partitioning function is based on the creation date of the record.
3. Create
a partitioning scheme to map the partitions of the partitioned table to the specified filegroup(s) and, thereby, to specific locations on the Windows file system.
4. Create
the table or index (or ALTER an existing table or index) by specifying the partition scheme as the storage location for the partitioned object.
Although Transact-SQL commands are available to perform every step described earlier, the Create Partition Wizard makes the entire process quick and easy through
an intuitive point-and-click interface. The next section provides an overview of using the Create Partition Wizard in SQL Server 2012, and an example later in this section shows the Transact-SQL commands.
Leveraging the Create Partition Wizard to Create Table and Index Partitions
The Create Partition Wizard can be used to divide data in large tables across multiple filegroups to increase performance and can be invoked by right-clicking
any table or index, selecting Storage, and then selecting Create Partition. The first step is to identify which columns to partition by reviewing all the columns available in the Available Partitioning Columns section located on the Select a Partitioning Column
dialog box, as displayed in Figure 3.13. This screen also includes additional options such as the following:
Figure 3.13. Selecting a partitioning column.
The next screen is called Select a Partition Function. This page is used for specifying the partition function where the data will be partitioned. The options
include using an existing partition or creating a new partition. The subsequent page is called New Partition Scheme. Here a DBA will conduct a mapping of the rows selected of tables being partitioned to a desired filegroup. Either a new partition scheme should
be used or a new one needs to be created. The final screen is used for doing the actual mapping. On the Map Partitions page, specify the partitions to be used for each partition and then enter a range for the values of the partitions. The
ranges and settings on the grid include the following:
Note
By opening the Set Boundary Values dialog box, a DBA can set boundary values based on dates (for example, partition everything in a column after a specific
date). The data types are based on dates.
Designing table and index partitions is a DBA task that typically requires a joint effort with the database development team. The DBA must have a strong understanding
of the database, tables, and columns to make the correct choices for partitioning. For more information on partitioning, review Books Online.
Enhancements to Partitioning in SQL Server 2012
SQL Server 2012 now supports as many as 15,000 partitions. When using more than 1,000 partitions, Microsoft recommends that the instance of SQL Server have at
least 16Gb of available memory. This recommendation particularly applies to partitioned indexes, especially those that are not aligned with the base table or with the clustered index of the table. Other Data Manipulation Language statements (DML) and Data
Definition Language statements (DDL) may also run short of memory when processing on a large number of partitions.
Certain DBCC commands may take longer to execute when processing a large number of partitions. On the other hand, a few DBCC commands can be scoped to the partition
level and, if so, can be used to perform their function on a subset of data in the partitioned table.
Queries may also benefit from a new query engine enhancement called partition elimination. SQL Server uses partition enhancement automatically if it is available.
Here’s how it works. Assume a table has four partitions, with all the data for customers whose names begin with R, S, or T in the third partition. If a query’s WHERE clause
filters on customer name looking for ‘System%’, the query engine knows that it needs only to partition three to answer
the request. Thus, it might greatly reduce I/O for that query. On the other hand, some queries might take longer if there are more than 1,000 partitions and the query is not able to perform partition elimination.
Finally, SQL Server 2012 introduces some changes and improvements to the algorithms used to calculate partitioned index statistics. Primarily, SQL Server 2012
samples rows in a partitioned index when it is created or rebuilt, rather than scanning all available rows. This may sometimes result in somewhat different query behavior compared to the same queries running on SQL Server 2012.
Administrating Data Using Partition Switching
Partitioning is useful to access and manage a subset of data while losing none of the integrity of the entire data set. There is one limitation, though. When
a partition is created on an existing table, new data is added to a specific partition or to the default partition if none is specified. That means the default partition might grow unwieldy if it is left unmanaged. (This concept is similar to how a clustered
index needs to be rebuilt from time to time to reestablish its fill factor setting.)
Switching partitions is a fast operation because no physical movement of data takes place. Instead, only the metadata pointers to the physical data are altered.
You can alter partitions using SQL Server Management Studio or with the ALTER TABLE...SWITCH
Transact-SQL statement. Both options enable you to ensure partitions are
well maintained. For example, you can transfer subsets of data between partitions, move tables between partitions, or combine partitions together. Because the ALTER TABLE...SWITCH statement
does not actually move the data, a few prerequisites must be in place:
• Partitions must use the same column when switching between two partitions.
• The source and target table must exist prior to the switch and must be on the same filegroup, along with their corresponding indexes,
index partitions, and indexed view partitions.
• The target partition must exist prior to the switch, and it must be empty, whether adding a table to an existing partitioned table
or moving a partition from one table to another. The same holds true when moving a partitioned table to a nonpartitioned table structure.
• The source and target tables must have the same columns in identical order with the same names, data types, and data type attributes
(length, precision, scale, and nullability). Computed columns must have identical syntax, as well as primary key constraints. The tables must also have the same settings for ANSI_NULLS and QUOTED_IDENTIFIER properties.
Clustered and nonclustered indexes must be identical. ROWGUID properties
and XML schemas must match. Finally, settings for in-row data storage must also be the same.
• The source and target tables must have matching nullability on the partitioning column. Although both NULL and NOT
NULL are supported, NOT
NULL is strongly recommended.
Likewise, the ALTER TABLE...SWITCH statement
will not work under certain circumstances:
• Full-text indexes, XML indexes, and old-fashioned SQL Server rules are not allowed (though CHECK constraints
are allowed).
• Tables in a merge replication scheme are not allowed. Tables in a transactional replication scheme are allowed with special caveats.
Triggers are allowed on tables but must not fire during the switch.
• Indexes on the source and target table must reside on the same partition as the tables themselves.
• Indexed views make partition switching difficult and have a lot of extra rules about how and when they can be switched. Refer to
the SQL Server Books Online if you want to perform partition switching on tables containing indexed views.
• Referential integrity can impact the use of partition switching. First, foreign keys on other tables cannot reference the source
table. If the source table holds the primary key, it cannot have a primary or foreign key relationship with the target table. If the target table holds the foreign key, it cannot have a primary or foreign key relationship with the source table.
In summary, simple tables can easily accommodate partition switching. The more complexity a source or target table exhibits, the more likely that careful planning
and extra work will be required to even make partition switching possible, let alone efficient.
Here’s an example where we create a partitioned table using a previously created partition scheme, called Date_Range_PartScheme1.
We then create a new, nonpartitioned table identical to the partitioned table residing on the same filegroup. We finish up switching the data from the partitioned table into the nonpartitioned table:
CREATE TABLE TransactionHistory_Partn1 (Xn_Hst_ID int, Xn_Type char(10)) ON Date_Range_PartScheme1 (Xn_Hst_ID) ; GO CREATE TABLE TransactionHistory_No_Partn (Xn_Hst_ID int, Xn_Type
char(10)) ON main_filegroup ; GO ALTER TABLE TransactionHistory_Partn1 SWITCH partition1 TO TransactionHistory_No_Partn; GO
The next section shows how to use a more sophisticated, but very popular, approach to partition switching called a sliding
window partition.
Example and Best Practices for Managing Sliding Window Partitions
Assume that our AdventureWorks business is booming. The sales staff, and by extension the AdventureWorks2012 database, is very busy. We noticed over time that
the TransactionHistory table is very active as sales transactions are first entered and are still very active over their first month in the database. But the older the transactions are, the less activity they see. Consequently, we’d like to automatically group
transactions into four partitions per year, basically containing one quarter of the year’s data each, in a rolling partitioning. Any transaction older than one year will be purged or archived.
The answer to a scenario like the preceding one is called a sliding window partition because
we are constantly loading new data in and sliding old data over, eventually to be purged or archived. Before you begin, you must choose either a LEFT partition function window or a RIGHT partition function window:
1. How
data is handled varies according to the choice of LEFT or RIGHT partition function window:
• With a LEFT strategy, partition1 holds the oldest data (Q4 data), partition2 holds data that is 6- to 9-months old (Q3), partition3
holds data that is 3- to 6-months old (Q2), and partition4 holds recent data less than 3-months old.
• With a RIGHT strategy, partition4 holds the holds data (Q4), partition3 holds Q3 data, partition2 holds Q2 data, and partition1
holds recent data.
• Following the best practice, make sure there are empty partitions on both the leading edge (partition0) and trailing edge (partition5)
of the partition.
• RIGHT range functions usually make more sense to most people because it is natural for most people to to start ranges at their lowest
value and work upward from there.
2. Assuming
that a RIGHT partition function windows is used, we first use the SPLIT subclause of the ALTER PARTITION FUNCTIONstatement
to split empty partition5 into two empty partitions, 5 and 6.
3. We
use the SWITCH subclause
of ALTER TABLE to
switch out partition4 to a staging table for archiving or simply to drop and purge the data. Partition4 is now empty.
4. We
can then use MERGE to
combine the empty partitions 4 and 5, so that we’re back to the same number of partitions as when we started. This way, partition3 becomes the new partition4, partition2 becomes the new partition3, and partition1 becomes the new partition2.
5. We
can use SWITCH to
push the new quarter’s data into the spot of partition1.
Tip
Use the $PARTITION system
function to determine where a partition function places values within a range of partitions.
Some best practices to consider for using a slide window partition include the following:
• Load newest data into a heap, and then add indexes after the load is finished. Delete oldest data or, when working with very large
data sets, drop the partition with the oldest data.
• Keep an empty staging partition at the leftmost and rightmost ends of the partition range to ensure that the partitions split when
loading in new data, and merge, after unloading old data, do not cause data movement.
• Do not split or merge a partition already populated with data because this can cause severe locking and explosive log growth.
• Create the load staging table in the same filegroup as the partition you are loading.
• Create the unload staging table in the same filegroup as the partition you are deleting.
• Don’t load a partition until its range boundary is met. For example, don’t create and load a partition meant to hold data that is
one to two months older before the current data has aged one month. Instead, continue to allow the latest partition to accumulate data until the data is ready for a new, full partition.
• Unload one partition at a time.
• The ALTER TABLE...SWITCH statement
issues a schema lock on the entire table. Keep this in mind if regular transactional activity is still going on while a table is being partitioned.
Thanks Shiven:) If Answer is Helpful, Please Vote

Create repository from database model- snowflake facts and dimension joins

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