Abstract: A method, system, and computer program product for generating checkpoint information in a database management system that determines the frequency of checkpointing of transactions based on a cost/benefit tradeoff analysis. A method for generating checkpointing information in a database management system comprises the steps of generating redo information based on transactions processed by the database management system, determining a cost of recovery using the redo information, determining a cost of taking a checkpoint, receiving a user specification of acceptable recovery delay and acceptable checkpoint overhead, and taking a checkpoint when cost effective to do so based on the cost of recovery using the redo information, the cost of taking the checkpoint and the user-specified acceptable delay and overhead.

Abstract: A device for objectively determining visual acuity includes a viewing screen on which a moving spot of light of diminishing intensity is projected. Infrared eye tracking sensors scan the eyes of the subject and generate a voltage analog signal of the eyes' position. The position signal is compared with a signal representing the position of the moving spot, and the difference is fed to a threshold detector circuit. As the spot becomes too dim to be seen by the subject, the eyes fail to track the spot, and the difference between the two signals surpasses the threshold of the detector circuit. The brightness of the spot when last tracked successfully, which correlates with standard visual acuity measurements, is then displayed as the visual acuity of the subject.