KNOWLEDGE BASE

Slow Extract Creation and Large Extract Size When Data Source Contains a Join


Published: 25 Oct 2021
Last Modified Date: 26 Oct 2021

Issue

When creating or refreshing an extract of a data source that contains tables combined using a join, the process may take much longer than creating or refreshing an extract of the individual tables, and the extract may also be much larger than extracts of the individual tables, or the extract creation or refresh may not complete.

Environment

  • Tableau Desktop

Resolution

Select the 'Physical Tables' data storage option ('Multiple tables' in Tableau 2018.3 to 2020.1) when creating the extract.

Cause

The 'Logical Tables' (previously 'Single table') data storage option creates a denormalized extract. If this option is used with a data source containing a join, the join is applied when the extract is created, and this results in an extract containing more records.
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