Method and apparatus for preventing dead-locks in distributed data base systems

摘要

Blocking events triggered in the individual nodes (K1 to K3) by subtransactions (STA...) ordered by a global transaction control are signalled to the global transaction control by blocking return message (SRM) which then informs all nodes in which subtransactions of the same global transaction (T...) are occurring, by means of blocking messages which leads to the associated subtransaction (for example STA 11, STA 21, STA31) being marked as "REMOTELY BLOCKED" in the respective local queuing table. Should a subtransaction of a global transaction run into a block due to a queuing graph (for example WG12) marked as "REMOTELY BLOCKED" or if a marking as "REMOTELY BLOCKED" is made for an existing queuing graph (WG22, WG32), a deadlock analysis (DLA) is triggered which is transferred step by step to the nodes concerned by means of the destination information associated with the blocking note until an open end of the global queuing graph formed by the local queuing graphs (for example WG12, WG22, WG32) via the respective row information is found or deadlock is determined. Extensive relief of the actual data processing by means of execution of these tasks by the control facilities for the distributed processing. IMAGE