1. A computer-implemented method for category-based search, the method executed by one or more computer systems and comprising: identifying an event comprising a user interaction with an article stored on a storage device of a client device responsive to monitoring user interactions with the client device; identifying an event schema describing a format of the identified event responsive at least in part to an article type of the article, the schema comprising fields based on the article type and fields that describe interactions with the article; identifying a plurality of attributes associated with the identified event that correspond to the fields based on the article type and fields that describe interactions with the article, the plurality of attributes identified responsive to the article and the monitored user interactions; determining at least a first category associated with the article based at least in part on the attributes; storing at least a first association data record, the association data record comprising a category-article pair identifier associating the first category and an article identifier identifying the article; receiving an implicit search query; causing the implicit search query to be executed on a data store comprising the first association data record; and receiving the first association data record from the data store.