19. The system of claim 15 , wherein the assigned tags are part-of-speech tags.
15. A system including memory and one or more processors operable to execute instructions, stored in the memory, comprising instructions to: obtain metadata for a document, wherein the metadata includes a sequence of terms; assign a tag to each term in the sequence of terms based at least in part on grammatical relationships between the terms, resulting in a corresponding sequence of tags; determine that the sequence of terms is grammatically correct based at least in part on tags within the corresponding sequence of tags; in response to the determination, store the sequence of terms as a query suggestion; in response to the determination, further calculate a suggestion score for the query suggestion based on one or more data points, wherein the suggestion score is stored with the query suggestion; receive a partial search query; select one or more query suggestions in the database for the partial search query based at least in part on the suggestion scores; and send the selected query suggestions in response to receiving the partial search query; wherein the instructions to obtain metadata for the document comprise instructions to segment the metadata within the document into a plurality of sequences of terms, wherein at least two of the plurality of sequences include at least some identical terms in different orders; and the instructions to assign a tag comprise instructions to assign a tag to each term in a given sequence of terms in the plurality of sequences of terms.