What are some examples of factless fact tables?
Common examples of factless fact table: Ex-Visitors to the office. List of people for the web click. Tracking student attendance or registration events.
What is factless table in DBMS?
It is essentially an intersection of dimensions (it contains nothing but dimensional keys). There are two types of factless tables: One is for capturing an event, and one is for describing conditions. An event establishes the relationship among the dimension members from various dimensions, but there is no measured value.
What is a reality table or fact table?
A reality or fact table’s record could be a combination of attributes from totally different dimension tables. The Fact Table or Reality Table helps the user to investigate the business dimensions that helps him in call taking to enhance his business.
What is a fact table in data warehouse?
Ralph Kimball’s dimensional data modeling defines three types of fact tables. These are: Transaction fact tables. Accumulating snapshot tables. In this post, we’re going to go through each of these types of fact tables, and then reflect on how they’ve not changed in the years since Kimball last updated the Data Warehouse Toolkit.
What is fact table and Factless table?
A factless fact table is a fact table that does not have any measures. It is essentially an intersection of dimensions (it contains nothing but dimensional keys). There are two types of factless tables: One is for capturing an event, and one is for describing conditions.
What is the difference between a fact table and a dimension table?
A fact table holds the data to be analyzed, and a dimension table stores data about the ways in which the data in the fact table can be analyzed.
What are the three types of fact tables?
There are three types of fact tables and entities: Transaction. A transaction fact table or transaction fact entity records one row per transaction. Periodic.
What are non-additive facts?
Non-additive Facts are Facts that cannot be summed up for any of the dimensions present in the Fact table. Eg: Facts which have percentages, Ratios calculated. Semi-Additive: Semi-additive Facts are Facts that can be summed up for some of the dimensions in the Fact table, but not the others.
What are different types of fact tables?
The Three Types of Fact TablesTransaction Fact Tables.Periodic Snapshot Tables.Accumulating Snapshot Tables.Why Have They Not Changed?
Is fact table normalized or denormalized?
A fact table is always DENORMALISED table. It consists of data from dimension table (Primary Key's) and Fact table has Foreign keys and measures.
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.
Which are two types of fact?
There are three types of facts:Additive: Additive facts are facts that can be summed up through all of the dimensions in the fact table.Semi-Additive: Semi-additive facts are facts that can be summed up for some of the dimensions in the fact table, but not the others.More items...
How many fact tables are there?
There are four types of fact tables: transaction, periodic snapshot, accumulating snapshot and factless fact tables.
What is factless fact table why we need it?
Factless tables simply mean the key available in the fact that no remedies are available. Factless fact tables are only used to establish relationships between elements of different dimensions. And are also useful for describing events and coverage, meaning tables contain information that nothing has happened.
What is additive and non-additive facts?
Additive facts are those facts which give the correct result by an addition operation. Examples of such facts could be number of items sold, sales amount etc. Non-additive facts can also be added, but the addition gives incorrect results. Some examples of non-additive facts are average, discount, ratios etc.
What is additive fact table?
Additive: Additive facts are facts that can be summed up through all of the dimensions in the fact table. A sales fact is a good example for additive fact. Semi-Additive: Semi-additive facts are facts that can be summed up for some of the dimensions in the fact table, but not the others.
What is a large dimension table?
Large Dimension Tables : Large dimension tables are very deep and wide. Deep means it has a very large number of rows and wide means it may have many attributes or columns. To handle large dimensions, one can take out some mini dimensions from a large dimension as per the interest.
What is a factless table?
Factless Fact Table. Factless tables simply mean the key available in the fact that no remedies are available. Factless fact tables are only used to establish relationships between elements of different dimensions. And are also useful for describing events and coverage, meaning tables contain information that nothing has happened.
Why do you need a fact table?
It is used to support negative analysis reports. For example, to create a report that a store did not sell a product for a certain period of time, you should have a fact table to capture all possible combinations. Then you can find out what is missing. Ex-Visitors to the office.
Is it difficult to change a customer's dimensions?
But in the case of customer dimensions, where a number of rows are millions and changes infrequently, then type 2 changes are feasible and not very difficult. If customer dimensions change rapidly, then Type 2 changes are problematic and difficult.
Do dimensions change over time?
Dimensions are generally constant over time, but if not constant, then they change slowly. The customer ID of the record remains the same but the marital status or location of the customer may change over time.
Factless fact table for event or activity
When designing a dimensional model, you often find that you want to track events or activities that occur in your business process but you can’t find measures to track. In these situations, you can create a transaction-grained fact table that has no facts to describe that events or activities.
Factless fact table for event or activity example
For example, you may want to track employee leaves. How often and why your employee leaves are very important for you to plan your daily activities and resources.
What is a factless table?
Factless Fact Table. A factless fact table is a fact table that does not have any measures. It is essentially an intersection of dimensions. On the surface, a factless fact table does not make sense, since a fact table is, after all, about facts.
Why is adding a fact that always shows 1 redundant?
However, adding a fact that always shows 1 is redundant because we can simply use the COUNT function in SQL to answer the same questions.
What is a factless table?
Factless fact table. A factless fact table is a fact table that does not have any measures. It is essentially an intersection of dimensions (it contains nothing but dimensional keys). There are two types of factless tables: One is for capturing an event, and one is for describing conditions.
What are the two types of factless tables?
There are two types of factless tables: One is for capturing an event, and one is for describing conditions. An event establishes the relationship among the dimension members from various dimensions, but there is no measured value. The existence of the relationship itself is the fact.
About Factless Fact Table
This tutorial assumes that the reader is familiar with SQL Server database and data warehouse business intelligence concepts. As well as is comfortable with the common terms used and applied in this field (of business intelligence).
When to use Factless FACT Tables
In order to understand the use of Factless FACT table we have to refer to, Kimball Group, one of the earliest pioneers in the field of Data Warehouse. According to Kimball Group, "It is possible that the event merely records a set of dimensional entities coming together at a moment in time.
How to use FactLess FACT Table
Let us now look at a common example of how to use a Factless Fact table.