On Serializability of Multidatabase Transactions Through Forced Local Conflicts

The main di culty in enforcing global serializability in a multidatabase environment lies in resolving indirect transitive con icts between multidatabase transac tions Indirect con icts introduced by local transac tions are di cult to resolve because the the behav ior or even the existence of local transactions is not known to the multidatabase system To overcome these problems we propose to incorporate additional data manipulationoperations in the subtransactions of each multidatabase transaction We show that if these operations create direct con icts between subtransac tions at each participating local database system indi rect con icts can be resolved even if the multidatabase system is not aware of their existence Based on this approach we introduce a multidatabase transaction management method that requires the local database systems to ensure only local serializability The pro posed method and its re nements do not violate the autonomy of the local database systems and guaran tee global serializability by preventing multidatabase transactions from being serialized in di erent ways at the participating database systems