Nested Transactions in a Combined IRS-DBMS Architecture

The possibility to put an Information Retrieval System (IRS)on top of a Data Base Management System (DBMS) is investigated with respect to concurrency control and recovery. The simple mapping of one IRS transaction to one DBMS transaction is analyzed and found to be unsatisfactory. Therefore, the idea of generating a sequence of DBMS transactions for a single IRS transaction is discussed. This notion of "nested" transactions assumes standard concurrency control technology but is applied twice: in the underlaying DBMS layer and in the IRS layer. The consequence is that multi-user control and recovery is also necessary in the IRS layer but it utilizes the concurrency control and recovery function of the DBMS.