Patent ID: 7174417

Claim:
A buffer allocation method supporting a maintenance policy in a shared disk-based multi Database Management System, the method comprising the steps of: (a) calculating a required buffer locking mode based on a scheme mode to buffer lock mode matrix (SMTBM) shown below when a block identifier, an access mode (read, write) and a consistency maintenance policy (detection, avoidance) are selected and a buffer manager is requested to allocate a block on a disk to access actual data; and (b) requesting a global locking manager to lock a buffer in the calculated buffer locking mode in case an obtained buffer locking mode is less than the calculated buffer locking mode or a version of a loaded block is lower than a required locking mode when the detection-based consistency maintenance scheme is selected, and approving buffer allocation otherwise, wherein a detection-based consistency maintenance scheme and an avoidance-based consistency maintenance scheme are integrated in a single procedure to interwork with each other; wherein, if using the detection-based consistency maintenance scheme and access mode is Read access, the required buffer locking mode is Weak Shared; wherein, if using the detection-based consistency maintenance scheme and the access mode is Write access, the required buffer locking mode is Weak Exclusive; wherein, if using the avoidance-based consistency maintenance scheme and the access mode is Read access, the required buffer locking mode is Shared; and wherein, if using the avoidance-based consistency maintenance scheme and the access mode is Write access, the required buffer locking mode is Exclusive.