Dataset settings
A dataset works with sources in direct access mode: DataLens runs all data queries on the source side. Dataset settings determine how the dataset uses the source data.
Connecting multiple tables
If multiple tables are available in the data source, you can merge them using the JOIN operator.
When the tables are joined, a link is created between them. When you create a link, you specify the fields from the source table and merged table.
You can use the following types of JOIN operators:
Default filters for new charts
In a dataset, you can create a default filter. It will be applied to any new chart created from data in the current dataset.
Note
- You can create a filter for an individual chart in the chart settings.
- Default filters are not applied to data in the dataset preview area.
Default filters for new charts will enable you to:
- Reduce the amount of data requested from a source when building a chart.
- Add customized filters to new charts created from data in the same dataset.
Running SQL queries in datasets
You can define a dataset data source using ad-hoc SQL queries over database connections. When a data source is accessed, the query code runs as a subquery. For more information about using SQL queries in a dataset, see Describing a dataset via a source SQL query.
When using SQL queries in datasets, we recommend:
- Restricting the user specified in the connection to
read-onlyaccess. - Assigning users that should not have ad-hoc query privileges the
Executeaccess to the connection and the associated datasets.
You can enable or disable the use of subqueries as a source when creating or editing a connection.
Default preview
By default, the dataset data uploaded from the source is displayed in the preview area. You can disable default data preview. To do this, click → Enable default preview in the top-right corner of the dataset and save the dataset. Now, when you open the dataset, the data will not appear in the preview area. To display the data, click Preview at the top of the screen.