A method utilizes data discovery to support visual analysis of datasets. A user selects a data source, and the method presents a natural language interface for analysis of the data source. A user specifies an incomplete natural language command directed to the data source, and the method correlates words in the incomplete natural language command with a data field in the data source. The method determines the data type of the data field and a range of data values for the data field. According to the data type and the range of data values, the method presents one or more autocompletion options for the incomplete natural language command. Each option includes respective text and a respective corresponding visual graphic. The user selects one of the autocompletion options, and the method forms a complete natural language command. The method then displays a data visualization according to the complete natural language command.