Deletes rows from a database table where the filtering clause of query is satisfied (i.e. the WHERE statement in generated SQL). Column selections and other settings of the query are ignored.
Under the hood, rows are deleted using SQL DELETE statement (with the WHERE statement from the query). The operation is atomic meaning that either all satisfying rows are successfully deleted, or nothing is deleted (in case of some failure).
Using a query in the transformation properties has the convenience of previewing what rows will be deleted before actually deleting them.
Note that this operation can't be undone – database rows are deleted forever.