Tableau Data Modeling and Layers (Physical & Logical) | #Tableau Course #33
Summary
TLDRThe video provides an introduction to data modeling in Tableau, explaining how to work with both the physical and logical layers of data. It covers four methods to combine tables: joins, unions, relationships, and data blending. The physical layer allows joins and unions between tables, while the logical layer uses relationships to abstract data and simplify visualizations. The video also touches on how to navigate between these layers and introduces data blending for combining data from different sources at the visualization level.
Takeaways
- 📊 **Data Modeling in Tableau**: Tableau allows creating a data model from a data source which can include multiple tables.
- 🔗 **Four Methods of Combining Tables**: Tableau offers relationships, joins, unions, and data blending to combine tables.
- 🏗️ **Physical and Logical Layers**: Tableau's data model consists of a physical layer with the actual data tables and a logical layer that abstracts these details.
- 🔄 **Joins and Unions in the Physical Layer**: In the physical layer, tables can be combined using joins or unions.
- 📚 **Logical Layer Abstraction**: The logical layer presents a single table (logical table) that can represent multiple physical tables, simplifying the data for visualizations.
- 🔗 **Relationships in the Logical Layer**: Relationships are used in the logical layer to connect logical tables, but they do not merge them into one.
- 🌐 **Data Blending at Visualization Level**: Data blending is used to combine data from different data sources for a single visualization.
- 📑 **Navigating Layers**: Users can navigate between the physical and logical layers within Tableau's data source page.
- 🔍 **Understanding Table Composition**: By hovering over icons in Tableau, users can see how logical tables are composed of physical tables.
- 🎥 **Supporting the Channel**: The script encourages viewers to like, comment, and support the content to help with YouTube algorithm visibility.
Q & A
What is a data model in Tableau?
-A data model in Tableau is a structure that defines how different tables in a data source are connected, helping organize and manage the relationships between tables for visualization.
What happens when your data contains only one table in Tableau?
-When your data contains only one table, the data model is very simple, with a single table representing the entire data source.
What are the four methods Tableau offers for connecting and combining tables?
-Tableau offers four methods for connecting and combining tables: relationships, joins, union, and data blending.
What is the difference between the physical layer and the logical layer in Tableau's data model?
-The physical layer consists of physical tables that can be joined or combined using unions, while the logical layer abstracts these physical tables into logical tables to simplify visualization by hiding underlying details.
How can tables be combined in the physical layer in Tableau?
-In the physical layer, tables can be combined using either joins or unions.
What is the role of relationships in the logical layer?
-In the logical layer, relationships are used to connect logical tables without merging them into one table, which allows each logical table to maintain its own structure.
How do joins and unions work in the physical layer?
-Joins in the physical layer combine rows from multiple tables based on a common field, while unions stack data from similar tables vertically, adding rows from one table to another.
What is data blending in Tableau?
-Data blending in Tableau is a method used to combine data from different data sources or data models at the visualization level, allowing for unified analysis.
How can you navigate between the physical and logical layers in Tableau?
-To navigate between the physical and logical layers, you can double-click on a logical table to enter the physical layer, and close it to return to the logical layer.
What are the steps involved in adding tables to the logical and physical layers?
-In the logical layer, tables are added as logical tables and connected using relationships. In the physical layer, tables can be added and combined using joins or unions.
Outlines
🔗 Introduction to Data Modeling in Tableau
This paragraph introduces the concept of creating a data model in Tableau. If the data contains only one table, the model is simple. However, real-life projects usually involve multiple tables, making things more complex. Tableau offers four methods to combine and connect tables: relationships, joins, unions, and data blending. The speaker mentions that a deep dive into these methods will follow, but first explains the basics of data modeling in Tableau.
🧩 Understanding Physical and Logical Layers in Tableau
This section explains the two layers involved in Tableau's data model: the physical layer and the logical layer. The physical layer contains actual tables, which can be combined using joins or unions. The logical layer provides an abstraction, simplifying visualization by hiding the complexity of multiple physical tables. The logical layer displays merged tables as a single flat table, referred to as a logical table. Relationships are used to connect logical tables, but no actual merging happens at this level. This abstraction helps simplify data representation during visualization.
🔄 Connecting Logical Tables with Relationships
This paragraph elaborates on how logical tables remain separate after relationships are created between them. Tableau only describes relationships between logical tables without merging them. Both physical and logical layers can be accessed via Tableau's data source page. When building visualizations, users see tables from the logical layer only, and any new data models from different sources can be connected through data blending at the visualization level. The distinction between physical and logical tables is crucial for understanding data modeling.
📊 Navigating Between Logical and Physical Layers in Tableau
Here, the speaker demonstrates how to navigate through the physical and logical layers in Tableau. When users drag and drop tables into the data model, they are considered logical tables by default. Relationships between these tables are created automatically. To access the physical layer, users need to double-click on a logical table, which reveals the underlying physical tables. In the physical layer, users can create joins or unions between tables, while the logical layer abstracts them as single logical tables.
🧮 Examining Relationships and Joins in Tableau
This section discusses how Tableau represents relationships and joins between physical tables. For instance, the speaker explains that a logical table can be made up of multiple physical tables combined through joins, which Tableau automatically detects. Users can hover over icons to view how physical tables define the logical table. In contrast, some logical tables, like 'Orders,' can directly pull data from the source system without any underlying physical tables. This flexibility allows users to efficiently manage different types of data connections in Tableau.
🚀 Conclusion: Summary of Tableau Data Modeling
In this final paragraph, the speaker recaps the concepts of navigating between physical and logical layers in Tableau. They highlight the importance of understanding the data modeling process and emphasize the upcoming lessons on how to combine tables using joins. The speaker also encourages viewers to support their YouTube channel by liking and commenting, noting that engagement helps with the YouTube algorithm. The video concludes with a brief farewell.
Mindmap
Keywords
💡Data model
💡Physical layer
💡Logical layer
💡Join
💡Union
💡Relationship
💡Data blending
💡Logical table
💡Data source
💡Visualization
Highlights
Connecting data to Tableau involves creating a data model.
Data models can be simple with a single table or complex with multiple tables.
Tableau offers four methods to combine tables: relationships, joins, Union, and data blending.
Data modeling in Tableau consists of a physical layer and a logical layer.
The physical layer may contain multiple tables combined using joins or Unions.
The logical layer provides an abstraction, hiding the details of the physical layer.
Merging tables in the physical layer results in a logical table in the logical layer.
Relationships in Tableau can only be established in the logical layer.
In the logical layer, tables cannot be merged into one; they can only be related.
Data sources in Tableau can be seen at the logical layer when building visualizations.
Logical tables can come directly from the source system, not just from physical tables.
Data blending allows combining data models or data sources at the visualization level.
Tableau's data modeling navigates between the physical and logical layers.
By default, Tableau starts at the logical layer in the data model.
Dragging tables into the data model at the logical layer creates relationships.
Accessing the physical layer is done by double-clicking into a logical table.
In the physical layer, joins and unions can be performed between tables.
Information about the composition of logical tables from physical tables is visible in Tableau.
Navigating between layers helps understand the data flow from physical to logical tables.
Learning how to combine tables in Tableau starts with understanding joins.
Supporting the channel helps improve visibility and reach.
Transcripts
okay so once we connect our data to
Tableau we have to create a data model
in our data source and if your data
contains only one table then your data
model is very simple you have single
table in your data model but in real
life projects things gets more
complicated where you have multiple
tables and Tableau here offers four
different methods of how to combine and
connect your tables we have
relationships joins Union and data
blending and now before we start doing
deep dive and those four methods let's
first understand the data moduling in
tableau
foreign
model we have two layers we have the
physical layer and on top of it we have
the logical layer in the physical layer
we might have some couple of physical
tables and we can combine them in
Tableau using two methods either joining
the tables or using Union between them
and now let's move to The Logical layer
it is the top level layer and provide us
like an abstract to hide all the details
in the physical layer this is especially
nice if we have a lot of tables in the
physical layer so once we are building
our visualizations we don't want to see
all those tables in the physical layer
so The Logical layer can provide us like
an abstract organ hide all those details
so the result of merging the tables
using join and Union in the physical
layer gonna be presented in The Logical
layer with single table flat table and
we call it a logical table so that means
we're gonna have two logical tables the
first one gonna present three tables
after doing the join and the 6 second
one can represent two tables using the
union but we still have a data modeling
to connect those two logical tables and
in Tableau we have only one method to do
that and we call it relationships and
it's very important to understand that
in The Logical layer we cannot merge
tables in one table so after
reconnecting them using the relationship
between the two logical tables the table
is going to stay as it is and nothing
can be merged we just described the
relationship between the two logical
tables and now back to those two layers
both of the physical layer and The
Logical layer we can find it inside
Tableau Data source and as you know on
top of the data source we have our
visualizations and you can see in this
example only the tables from The Logical
layer and you can start building your
visualizations using the data available
from The Logical layer but sometimes as
you are working with the projects you
build another data source with another
data model and here in this example it's
important to understand that that's not
all logical tables comes from the
physical tables they could come directly
from your Source system and now in order
to build one visualizations from both of
the data models and the data sources we
have somehow to connect those two data
models or data sources and we can do
that in the visualization level where
Tableau offer us the last and very
unique method of connecting and
combining tables something called Data
blending so by looking at this you can
see that Tableau offer us four different
methods of how to combine and connect
tables in different layers and different
levels so in the physical layer we have
the joins and unions we have in the
logical layer the relationships and add
the visualization level we have data
blending
foreign
how we can navigate through the physical
and The Logical layer we are currently
at the data source page and as a default
we're gonna be at The Logical layer in
the data model so that means anything
that we drag and drop in our data model
gonna be considered as a logical table
so the customers is a logical table
let's take another one let's take the
orders drag and drop it over here so
this is our second logical table and as
you can see Tablo did create between
them a relationship because at the
logical layer we can do only
relationships so now we are at The
Logical layer how we can go to the
physical layer in order to do that we're
gonna go inside a logical table so let's
go to the customers and double click on
it once we do that we're gonna go to the
second layer we are inside the physical
layer now so Tableau can tell you over
here the customers is made of one table
because we have only one physical table
so now anything that we drag and drop in
the data model going to be considered as
a physical table so for example we can
take the customer details let's drag and
drop it over here and by default Tablo
going to create between them not a
relationship it's going to create a join
between those two physical tables and of
course we can do a union between them so
in the physical layer we can do joins
and unions and as you can read over here
it says the customers The Logical table
customers is made of two physical tables
and if you hover on this icon you will
see exactly that so we have two physical
tables defines the logical table
customers and now if you want to go up
back to the logical layer we can do that
by just closing the physical layer so
let's click on that and now you can see
that the customers has a new icon it
says in the physical layer there is like
a join and we get more informations if
we hover on the tables it says logical
table customers that is made of two
physical tables the customers and the
customers details so that means the data
and The Logical tables comes from the
physical player but if we go to the
orders over here you will see no
physical tables the data comes directly
from the original tables and with that
we have learned how to navigate through
the physical and The Logical layer
alright so with that we have learned the
data moduling in Tableau and what is the
physical and logical layers next we will
start learning how to combine tables in
Tableau and we will start with joins and
if you like my content and you want to
support the channel then I really
appreciate it if you support like and
comment it's really going to help the
YouTube algorithm thank you so much for
watching and I will see you in the next
video bye
foreign
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