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2. Data Source Filters
If you are connecting to a Live database with a large amount of data, you may want to use data source filters to reduce the amount of data appearing in the Tableau view.
Data source filters
- Normally reside between the data source (normally an extract) and the Tableau workbook
- Does not reduce the size of an extract but limit the amount of data that appears in the Tableau workbook
- Very useful when working with large extracts in a shared folder
- Helpful when you make a Live connection to a data source and extract filters are not possible
In the previous lesson we saw how extract filters worked by reducing the size of the data source that was stored in the Tableau extract.
As a result, the performance of the Tableau workbook can be improved substantially.
Data source filters are one level up.
And occur between the Tableau workbook and the data source.
When a Tableau workbook executes a query on a data source the data source filter kicks in automatically and is applied with the query.
So when would we use a data source filter instead of an extract filter.
Well sometimes, you may be sharing an extract with a colleague or among different Tableau workbooks.
You may not want to create a new extract but you do want to apply filters to the data source for different use cases.
Alternatively, you may have a live connection between a data source and a Tableau workbook and an extract filter is not an option.
Typically, I tend to use extract filters instead of data source filters to ensure that I don't have any unnecessary data in my extracts.
But on these occasions that I have shown here, data source filters do serve a purpose.
Data source filters are very easy to create.
In the data source view, we simply go to the top right-hand corner and add a filter.
This gives me the dialogue box for data source filters and I can simply add a filter based on a dimension or measure.
And here, I am going to choose payment date.
Then I'll press OK.
I'll go with the range of dates.
And in this example, I only want dates from the second half of the year.
So, I'll move the month to July.
Then I'll press OK.
And I will add another filter And this time around, I am only going to pick transactions from the sales person, Palacios I'll then press OK.
And then OK again.
And as you can see, my dataset updates accordingly.
As I scroll across, you'll see that the sales person Palacios is the only one in my column and you can also see that the payment dates are all after the first of July.
To remove these filters, simply go back to edit select the filter in question and remove And we're now back to our original dataset again.
In this view, we have now covered extract filters and data source filters.
In the next couple of lessons, we'll look at more high-level filters starting with context filters which would be setup in the view.