1. A data processing method comprising: identifying, at an application server separate from a database system, one or more tenant identifiers that each identify a unique tenant associated with a data store; sending instructions to the database system for partitioning a data table into one or more partitions, wherein the data table is associated with a first functionality of an application hosted by the application server, and wherein the first functionality relates to subject-specific data attributes, wherein each partition is associated with a particular tenant identifier of the one or more tenant identifiers and comprises data associated with the particular tenant identifier; sending instructions to the database system for partitioning a particular partition from the one or more partitions into one or more sub partitions; determining a custom sub partition key corresponding to the one or more sub partitions, wherein each custom sub partition key is associated with the first functionality of the application corresponding to the data table; associating the custom sub partition key, at least in part, with the particular tenant identifier; in response to receiving a data access query associated with the particular tenant identifier, determining a data attribute necessary for the data access query; determining a particular custom sub partition key that is associated with the particular tenant identifier and the data attribute; preparing a database query using the particular custom sub partition key; sending the database query to the database system for execution against a data table; and receiving, from the database system, a result of executing the database query against the data table.