1. A database system that provides access to a compressed set of records respectively having a record identifier, the database system involving a device having a processor and comprising: a delta store that stores records indexed by a record key; a delete bitmap that stores record identifiers of records in the compressed set that have been deleted; a delete buffer that also that stores record identifiers of records in the compressed set that have been deleted; and a memory storing instructions that, upon execution by the processor, cause the database system to: fulfill a request to insert an inserted record into the compressed set by initially inserting the inserted record into the delta store rather than into the compressed set; fulfill a request to update an updated record of the compressed set by initially updating a version of the record in the delta store rather than in the compressed set; fulfill a request to delete a selected record from the compressed set by initially storing the record identifier of the deleted record in the delete buffer rather than deleting the record from the compressed set; periodically update the compressed set to: transfer inserted records in the data store into the compressed set, and transfer the record identifiers from the delete buffer to the delete bitmap; and fulfill a query over the compressed set by aggregating: matching records in the delta store; and matching records in the compressed set that are absent from the delta store, the delete buffer, and the delete bitmap.