Segmented main-memory stored relational database table system with improved collaborative scan algorithm

摘要

In a computerized distributed environment a system is described that exhaustively scans at least one memory segment of a database relational table during successive continuous scanning cycles. The scanning system comprises a first and a second cursor adapted to exhaustively scan the one or more memory segments at each scanning cycle in order to process pending update and query database operations. The first cursor is a write cursor configured to write into the one or more memory segments and process database operations aimed at updating data records into the relational table. The second cursor is a read cursor configured to read out from the one or more memory segments relational table data records in response to a query. The scanning system is characterized in that the first cursor is further configured to write relational table data records into the one or more memory segments before the second cursor can read them, and in that the time delay between the first cursor writing and the second cursor reading is less than one scanning cycle. Query database operations are reordered to perform query-data joins. The database update operations include updating, deleting and inserting relational table data records. They are processed in their order of arrival. Also, query and update database operations are reordered to perform query/update-data joins.