Methods, systems and apparatus, including computer programs encoded on computer storage media for compressing sensor log information. One of the methods includes accessing log information maintained in one or more databases, the log information being generated in response to actions associated with entities, and the log information indicative of respective sessions for which one or more logs were generated, each log indicating an entity. Log information is grouped according to entity. One or more logs associated with respective sessions based on the grouped log information. Compressed logs are generated from logs associated with respective sessions based on compression rules.