If we have two connection with same data source which is sql server what is the difference between Join and Blending in this case if we use join instead of doing blending between those tables which have been used in both connection?
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2 Answers
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Joins are done at the row level. You need to have a relationship between the two tables. Joins extend the number of columns of both tables by adding new columns.
Blending is done at the aggregate level. You need to aggregate at least one, or both, of your data sources using sum, min, max, etc.
You can read more about blending vs joining and there are many other sources out there as well through Google.
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There are lots of differences between blends and joins, even if the data source is the same. One such is that blends perform a certain amount of automatic aggregation on the secondary data source.
Another will be performance: Joins from the same data source will be handled by that database server, and typically perform better than blends that may need to be handled by Tableau.
There are many other differences, and results will vary with the structure of your data. I suggest you refer to Tableau's docs on the matter, which nicely encapsulate the differences and use cases: https://onlinehelp.tableau.com/current/pro/desktop/en-us/multiple_connections.htm
