Data, such as product data or airline flight data, is represented using structured data tuples, tables, or as data with related metadata and tags, and stored by a search engine. Partial queries are received by the search engine from a user and are used to generate a dialog between the search engine and the user. The dialog may include suggested query completions for the partial queries that correspond to a schema associated with the data tuples. The suggested query completions may be determined using attribute combinations of attributes and attribute values, or metadata and tags associated with the data tuples, including known synonyms and misspellings. The user may interact with the query completions in the dialog, and the search engine may revise the dialog and the query completions according to the interactions. A user may query data tuples without knowing the schema used by the underlying data structures.