Creating an Extract

1. Select a data source on the Data menu and then select Extract Data to open the Extract Data dialog box.
   
   
   
2. Optionally define filters to limit the data that will be extracted. Any fields that are hidden in the Data window will be automatically excluded from the extract. Click the Hide All Unused Fields button to quickly remove them from the extract.
   To add filters, click the Add button under the Filters list.
3. Specify whether to Aggregate data for visible dimensions. When you select this option the measures are aggregated using their default aggregation. Aggregating the data can minimize the size of the extract file and increase performance.
   When you choose to aggregate the data you can also choose to Roll up dates to a specified date level such as Year, Month, etc.
   
   
   
   The examples below show how the data will be extracted for each aggregation option.

   Original Data		Each record is shown as a separate row. There are 7 rows in the data source.
   Aggregate Data (no roll up)		Records with the same date and region have been aggregated into a single row.There are 5 rows in the data source.
   Aggregate Data (roll up dates to Month)		Dates have been rolled up to the Month level and records with the same region have been aggregated into a single row.There are 3 rows in the data source.

4. Select the number of rows you want to extract. You can extract All, the Top N rows, or a Sample from the data source. Tableau first applies any filters and aggregation and then extracts the number of rows from the filtered and aggregated results.
   The number of rows options depend on the type of data source you are extracting from. For example, not all data sources support sampling so that option is not always available.
5. When finished, click Extract.
6. In the subsequent dialog box, select a location to save the extract into and give the file a name. Then click Save.

Depending on the size of your data source, extracting data can take a long time. However, after you have extracted the data and saved it to your hard drive, performance will improve.