Tableau Union

Introduction

To consolidate data from several tables or data sources with the same structure into a single table in Tableau, utilize the "union" operation. This is especially helpful if you want to combine similar data that are dispersed across several tables or sources for analysis or visualization.

The steps to execute a union in Tableau are as follows:

Connect to Data: To begin, establish a connection between Tableau and the data sources that hold the tables you wish to union.

Drag Tables: In Tableau, drag and drop the tables you wish to combine from the Data pane on the left sidebar onto the canvas.

Form a Union:

Choose the first data source or table.
Click on the second table or data source that you wish to union while holding down the Ctrl (or Cmd on a Mac) key.
To select a table, right-click on it and select "Union."

Mapping Fields: Tableau will present a unified view of the tables with fields from both tables after establishing the union. If the fields have different names but represent the same data, you may need to map the fields (matching the corresponding fields).

Work with Unioned Data: You can use the unified data source in Tableau in the same way as any other data source after the union has been created and the fields have been mapped. This aggregated dataset can be used for analysis, filtering, and visualization.

Refresh or Edit Union: Open the Data menu, select your unioned data source, and then click "Edit Relationships" or "Edit Data Source" to make the necessary changes if the underlying data changes or you need to edit the union.

Recall that Tableau can only execute unions if the data structures in the merged tables are similar to one another. Before constructing a union, you might need to carry out data cleaning or transformation if the tables have different structures or if the data is incompatible.

What does tableau union serve as?

There are multiple uses for the Tableau union function in data analysis and visualization.

Data Consolidation: Frequently, similar information is dispersed among several tables or sources. By uniting these disparate datasets into a single source through union, you can more easily analyse and visualize the consolidated data.
Simplified Analysis: Analysis is made simpler by creating a unified view through the union of similar datasets. It streamlines the investigation of data relationships and patterns by doing away with the need to flip between several tables or data sources.
Comparative Analysis: By uniting multiple datasets with similar structures (such as sales data from various locations or time periods), you can easily compare them side by side, identify trends, and find variations or correlations between the datasets.
Effective Reporting: A union aggregates all pertinent data for reporting purposes, particularly when data is fragmented across multiple databases or files. This guarantees thorough insights and simplifies reporting procedures.
Ease of Visualization: When a union produces a single dataset, creating visualizations in Tableau becomes more efficient. Without having to switch between different sources, it enables the creation of thorough dashboards and visual representations of the combined data.
Enhanced Data Blending: When paired with Tableau's data blending function, Union can be especially helpful. It eliminates the need for conventional database joins by enabling you to join data from several sources based on comparable dimensions, resulting in a more extensive dataset for analysis.

By combining compatible data from multiple sources into a single, coherent view, Tableau's union function essentially speeds up the data preparation process and enables analysts and data professionals to work with related datasets more effectively and obtain deeper insights.

Advantages

The union functionality in Tableau has the following benefits:

Simplified Data Management: Union makes data management easier by allowing you to combine related datasets from several sources into a single one. You deal with a single, cohesive dataset as opposed to multiple distinct tables or files.
Streamlined Analysis: The analysis process is made simpler by combining data using union. With a consolidated dataset, you can conduct analysis, produce visualizations, and gain insights without having to switch between different data sources.
Holistic Insights: You can obtain a comprehensive understanding of the information by combining related data from various sources or time periods. A deeper comprehension of the relationships within the data and more informed decision-making are made possible by this holistic viewpoint.
Effective Reporting: Combining datasets makes it easier to create thorough reports. By ensuring that all pertinent data is included, it removes the need for manual data merging or aggregation during the reporting process.
Enhanced Visualization: The visualization process is more effective when there is only one dataset produced by a union. You can produce logical and educational dashboards, reports, and visualizations to convey insights more successfully.
Time-saving: Union saves time by lowering the amount of work needed to prepare the data. Tableau's union feature automates the process of manually combining or organizing multiple datasets, saving a significant amount of time.
Flexibility in Data Sources: Tableau gives you the ability to combine data from a variety of sources, including cloud-based platforms, Excel files, and databases. Users can work limitlessly with data from various systems thanks to this flexibility.

Disadvantages

Although Tableau's union functionality has many benefits, there are a few things to think about and possible downsides to be aware of:

Data Compatibility: When merging datasets with comparable structures, union performs best. Additional data cleaning and manipulation may be necessary when merging data that has different formats, inconsistent schemas, or incompatible data types. This process can take a while.
Impact on Performance: Performing unions across numerous data sources or working with sizable datasets can have an effect on performance. In particular, if the data sources are complicated or need a lot of processing, it could slow down the processes involved in data retrieval, analysis, or visualization.
Complexity in Joining Unrelated Data: Union is appropriate for merging related datasets, but if there is no obvious relationship between the data or if trying to join unrelated data results in confusion or incorrect analysis, it may not be possible.

Conclusion

In conclusion, Tableau's union feature is effective for combining data and simplifying analysis, but it needs to be used with caution when it comes to data compatibility, possible performance effects, and maintenance issues.