39. A non-transitory computer-readable storage medium on which is encoded executable program code for category-based search, the program code comprising: program code for 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; program code for 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; program code for creating a category associated with the article based at least in part on the fields that describe interactions with the article; program code for storing an association data record, the association data record comprising a category-article pair identifier associating the category and an article identifier identifying the article; program code for receiving an implicit search query; program code for causing the implicit search query to be executed on a data store comprising the association data record; and program code for receiving the association data record from the data store.
39. A non-transitory computer-readable storage medium on which is encoded executable program code for category-based search, the program code comprising: program code for 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; program code for 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; program code for creating a category associated with the article based at least in part on the fields that describe interactions with the article; program code for storing an association data record, the association data record comprising a category-article pair identifier associating the category and an article identifier identifying the article; program code for receiving an implicit search query; program code for causing the implicit search query to be executed on a data store comprising the association data record; and program code for receiving the association data record from the data store. 41. The computer-readable storage medium of claim 39 , wherein the category comprises a first category, the association data record comprises a first association data record and the article comprises an article attribute, further comprising: program code for determining a second category associated with the article based at least in part on the article attribute; and program code for storing a second association data record, the second association data record comprising a category-article pair identifier associating the second category and the article identifier identifying the article.