1. A method for supporting multitenant data in a multitenant system, the method comprising: configuring a multitenant application to be used by a plurality of tenants, wherein each tenant of the plurality of tenants is associated with a different tenant discriminator value identifying said tenant; storing data for use by said multitenant application in a table corresponding to an entity defined by said multitenant application such that columns of the table correspond to properties of the entity, wherein said table is a shared multitenant table in which all of said data for all of the plurality of tenants is co-located, and wherein said table holds a plurality of rows of data from each of said plurality of tenants; providing said table with a tenant discrimination column for holding tenant discriminator values which identify which of said plurality of rows of data held in said table is associated with which particular tenant of the plurality of tenants; creating a plurality of entity managers including an entity manager for each tenant of said plurality of tenants, wherein the entity manager associated with each tenant of said plurality of tenants is configured with the tenant discriminator value associated with said each tenant of said plurality of tenants by one of the multitenant application or a shared entity manager factory configured to create the plurality of entity managers; creating a plurality of transactional entity instances, using said multitenant application, for each of said plurality of tenants, wherein each of said plurality of transactional entity instances is associated with a particular row of data of said plurality of rows of data and with a tenant discriminator value used to identify a particular one of said plurality of tenants, and wherein each of said plurality of transactional entity instances is associated with a transaction performed by said multitenant application on said row of data held in said table and identified by the tenant discriminator value associated with said entity instance; providing a plurality of caches, wherein a different one of said plurality of caches is associated with each particular one of the plurality of tenants; and using each cache to manage transactional entity instances associated with said particular one of said plurality of tenants associated with the cache.