What is extended star schema in SAP BW?
What is extended star schema in SAP BW?
In an extended star schema, you have the fact and dimension tables inside the cube, however SID tables are outside the cube. When you load the transactional data into the Info cube, the Dim Id’s are generated based on SID’s and these Dim ids’ are then used in the fact tables.
What is the maximum number of tables that can be joined in a star schema?
Theoretically, there is no upper limit on the number of tables that can be joined using a SELECT statement. (One join condition always combines two tables!) However, the Database Engine has an implementation restriction: the maximum number of tables that can be joined in a SELECT statement is 64.
What is star schema in BI?
A star schema is a database organizational structure optimized for use in a data warehouse or business intelligence that uses a single large fact table to store transactional or measured data, and one or more smaller dimensional tables that store attributes about the data.
What is extended star topology?
A hierarchical or extended star topology is a star network with an additional networking device connected to the main networking device. Typically, a network cable connects to one switch, and then several other switches connect to the first switch.
Can a star schema have more than 4 dimensions?
The KimballGroup states that 5 to 15 dimensions is usually the most common range and that is at the PHYSICAL LEVEL. The only thing I would add is that 3 role playing dimensions based off the same PHYSICAL dimension do not count as anthing more than 1 dimension within the context of Kimball’s statement.
What are the three types of entities in a star schema?
The Star Schema Design Pattern. A star schema consists of one fact table, and one or more dimension tables. The fact table contains information about changes. In the most basic kind of fact table, each row represents a transaction.
What is difference between star and snowflake schema?
A star schema contains both dimension tables and fact tables in it. A snowflake schema contains all three- dimension tables, fact tables, and sub-dimension tables. It is a top-down model type. It is a bottom-up model type.
Which schema is best for Power BI?
star schema
Power BI engine works best with star schema. For example, the sales table exists on the many side of the relationship and all the dimension tables exist on the 1 side of the relationship as shown below.
Why star schema is used in Power BI?
Star schema is a mature modeling approach widely adopted by relational data warehouses. It requires modelers to classify their model tables as either dimension or fact. Dimension tables describe business entities—the things you model. Entities can include products, people, places, and concepts including time itself.
Why do we use extended star topology?
It is the extended version of the star topology. This topology helps to control multiple nodes at the same time. The data can be easily transmitted across the network and there is less chance of network failure compared to other topologies. The central hub controls the whole network in the extended star topology.
How do you differentiate distributed star from extended star topology?
Star Topology In an extended star, repeaters are introduced between the hub and the network nodes. The repeaters are used to increase the distance over which signals can travel. A distributed star is formed by the interconnection of two or more individual star networks.
What is InfoCube and InfoObject?
An InfoCube is used to store the data physically. It consists of a number of InfoObjects that are filled with data from staging. It has the structure of a star schema. The real-time characteristic can be assigned to an InfoCube. These Real-time InfoCubes are used differently to standard InfoCubes.
How many types of DSO are there in SAP BW?
three tables
Types of DataStore Objects
| Type | Structure | SID Generation |
|---|---|---|
| Standard DataStore Object | Consists of three tables: activation queue, table of active data, change log | Yes |
| Write-Optimized Data Store Objects | Consists of the table of Active data only | No |
| DataStore Objects for Direct Update | Consists of the table of Active data only | No |
Can we have more than 1 fact table?
A data warehouse can have more than one fact table. However, you do want to minimize joins between fact tables. It’s ok to duplicate fact information in different fact tables.
Can we have 2 fact tables in star schema?
Star schema contains only one fact table.
What is the difference between a star schema and a snowflake schema?
Star schema stores redundant data in dimension tables, while snowflake schema fully normalizes dimension tables and avoids data redundancy.
Can we join 2 fact tables?
The answer for both is “Yes, you can”, but then also “No, you shouldn’t”. Joining fact tables is a big no-no for four main reasons: 1. Fact tables tend to have several keys (FK), and each join scenario will require the use of different keys.