What is factless fact table in dimensional model?
Factless fact table for event or activity When designing 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.
Are customer communications events or factless fact tables?
Likewise, customer communications are events, but there may be no associated metrics. Factless fact tables can also be used to analyze what didn’t happen. These queries always have two parts: a factless coverage table that contains all the possibilities of events that might happen and an activity table that contains the events that did happen.
What are the two parts of a factless query?
These queries always have two parts: a factless coverage table that contains all the possibilities of events that might happen and an activity table that contains the events that did happen. When the activity is subtracted from the coverage, the result is the set of events that did not happen.
What is a fact table in data warehousing?
However, there are situations where having this kind of relationship makes sense in data warehousing. For example, think about a record of student attendance in classes. In this case, the fact table would consist of 3 dimensions: the student dimension, the time dimension, and the class dimension.
What is a factless fact?
Factless facts are those fact tables that have no measures associated with the transaction. Factless facts are a simple collection of dimensional keys which define the transactions or describing condition for the time period of the fact.
What is a factless fact table in ETL?
A factless fact table is a fact table that does not have any measures, i.e. any numeric fields that can be aggregated. For example, if you are modelling product sales, you can have a Sales fact table that will contain the dimension keys and, for example, the "amount" value/measure, to record the amount sold.
How many attributes does factless fact table have?
There are two kinds of factless fact tables: Factless fact table describes events or activities. Factless fact table describes a condition, eligibility, or coverage.
What are dimensions and fact?
Facts and dimensions are data warehousing terms. A fact is a quantitative piece of information - such as a sale or a download. Facts are stored in fact tables, and have a foreign key relationship with a number of dimension tables. Dimensions are companions to facts, and describe the objects in a fact table.
What are junk dimensions?
A Junk Dimension is a dimension table consisting of attributes that do not belong in the fact table or in any of the existing dimension tables. The nature of these attributes is usually text or various flags, e.g. non-generic comments or just simple yes/no or true/false indicators.
What is factless fact in Microstrategy?
A factless fact table is table that doesn't have fact at all. They may consist of nothing but keys. There are tow types of factless fact table. 1-> event 2-> coverage.
What is true about 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.
How many dimensions should a fact table have?
In this model, we have a single fact table surrounded by three dimension tables. Our foreign keys for the fact table include: time_id – refers to the time dimension table ( dim_time ) product_id – refers to the product dimension table ( dim_product )
What are the 3 types of fact tables?
These are:Transaction fact tables.Periodic snapshot tables, and.Accumulating snapshot tables.
How do you identify fact and dimension?
Fact table is located at the center of a star or snowflake schema, whereas the Dimension table is located at the edges of the star or snowflake schema. Fact table is defined by their grain or its most atomic level whereas Dimension table should be wordy, descriptive, complete, and quality assured.
What are the different types of facts?
We can divide the Facts in to these three types.Non-Additive.Semi-Additive.Additive.
What is the difference between fact data and dimension data?
Fact tables comprises of the facts of the system as its data content, and Dimension tables comprises of all the properties or objects of the fact tables that can help to connect fact tables to the respective dimension tables.
What is a factless table?
By definition, the factless fact table is a fact table that does not contain any facts. There are two kinds of factless fact tables: 1 Factless fact table describes events or activities. 2 Factless fact table describes a condition, eligibility, or coverage.
Can you find measures to track in a dimensional model?
When designing 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. Even though there are no facts storing in the fact table, the event can be counted to produce very meaningful process measurements.
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.
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.
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.