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To improve performance when working with extracts you can optimize the extract. Optimizing an extract creates secondary structure in the extract that speed up future queries.
Optimize the extract by selecting a data source on the Data menu and then selecting .
The following types of optimizations are made:
Calculated fields are computed in advance and stored in the extract. In future queries, Tableau can look up the already computed value rather than running the computation again. The following types of calculated fields ARE NOT materialized:
In addition, if the formula for a materialized calculation changes or the calculation is deleted from the data source, the materialized calculation is dropped from the extract until the extract is optimized again.
When a workbook contains filters that are set to show only relevant values, computing the available values for that filter can be an expensive query. For these filters, Tableau must evaluate the other filters in the workbook first and then compute the relevant values based on their filter selections. To speed up these queries, a view can be created that computes the possible filter values and caches them for faster lookup later.