Can someone give me an example and explain why link tables must be preferred over concatenation to remove synthetic keys.I am aware that when granularity of tables is different we opt link table over concatenation option. I want to see how concatenation affects data when granularity is different
Both the methods have their own advantages, it really depends on the the business requirements.
If in the source tables you have multiple fields in common and if the granularity is the same (e.g. amounts aggregated per month - Actual, Forecast or Budget) the concatenation will be a good option as it will merge data in a simple and with improved performance when it comes to handle large volumes of data.
Link Tables allow you to create more understandable data model for end users, but my advise is that you use it only when you have few similar fields between tables 2-3, and the table size is not huge, as it may generate performance issues.
Hope it helps.
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IMO a different granularity between fact-tables is not mandatory a show-stopper for a concatenation. We are using it often by sales on a daily level and budgets on a monthly level - see for example: Fact Table with Mixed Granularity - Qlik Community - 1468238.
Hope this resolve your issue. If the issue is solved please mark the answer with Accept as Solution & like it. If you want to go quickly, go alone. If you want to go far, go together.
