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Tableau public sample data sets3/3/2023 I think that this new model will not work with the custom SQL data sources, which the joins are fulfilled by SQL instead of diagram links in Tableau. More tests and practices are needed to see if there will be no interfere with LOD, filters and other Tableau concepts. I would rank this improvement as the secondly most important progress which just follows "Level of Detail Expressions" function, which was added in Tableau 9. Hi Ken, thanks for the "early bird" blog which analyzes and discusses the new data model. For more information on this feature, see Assuming Referential Integrity for Joins. But, you must also be careful-if you select this option and your database does not have referential integrity, it could produce inaccurate results. This will, of course, result in a more efficient SQL statement. If you use the "Assume Referential Integrity" option, Tableau will eliminate (cull) the join when that table is not required on the view. Note: As Zen Master, Tamas Foldi, pointed out to me, my above statement is not exactly true (I should know better than to use the word "always" when discussing anything related to Tableau as it seems there is "always" another option □). The tables in your model, joined exactly how you’ve instructed it to do so. The SQL may retrieve different fields and may performĭifferent types of aggregations, but the FROM clause will always include all You create the basic structures, then all of the SQL executed will pullįrom that same structure. The key point here is that the old data model is “set-in-and-forget-it”. Additionally, some people may notĮven realize that their join has led to data duplication and, thus, don’t know Readily accessible to new users of Tableau. Unfortunately, LODs are a bit tricky and not The typical solution to this problem is the use of a Level-of-DetailĬalculation (see use case # 1 in 20 Uses for Level-of-Detail Calculations). Pretty much the same SQL (except using People_Multiple instead of People),īut because of the record duplication, our resulting Sales aggregates are doubled. Only part of the problem-aggregations are also impacted by this data duplication.įor example, let’s create that bar chart showing Sales by Customer again. If you’re dealing with millions of records, thisĭuplication could prove to be a huge constraint. The result set is 19,988 records, as opposed to the 9,994 But, because there are two people for each region, each record in Orders When we use this in our data model, it executes a similar SQL statement as shownĪbove. Yourself, the connection information is available on the SQL for Tableau UsersĪs you can see, this table has two people for each region. Finally, these tests will be performed using my publicly-available Learn, feel free to check out my series on SQL for Tableau Users. If you do not have a SQL background and want to While I’ll be simplifying this SQL a bit for readability, I am assuming some Model is doing, we’re going to be looking at the SQL generated by Tableau. Second, in order to understand exactly what the data Interested in digging a bit deeper, you can also read The Tableau Data Model and Relationships, Part 1: Introducing New Data Modeling in Tableau. Of “relationships” and generally how they differ from joins. It will give you an overview of the new concept Video on How Relationships Differ from Joins. First, if you’re not yetįamiliar with the new data model, I’d suggest that you start by watching the short
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