A scalable data structure for real-time estimation of resource availability in build-to-order environments

This paper defines a highly scalable interval index structure called the Temporal Bin tree (TB-tree) that can be embedded in any resource planning application whose algorithms require efficiently estimating either the time that a resource will be available to process a specific task of known length or the net availability of a resource during a specified period of time. It is specifically engineered to meet the real-time response and space efficiency requirements of large-scale resource planning applications that are required for mass customization. Basically, the TB-tree is a binary tree structure that represents availability of a resource across a planning horizon. Representing intervals of availability hierarchically using a tree structure increases the efficiency of search for resource availability when the discretization of time is fine-grained or the planning horizon is long. The tree forms a backbone structure that does not require disruptive rebalancing during update operations, which would mitigate the ability of the tree to respond to queries in real time. Its specific implementation allows for random access at any level of the tree to further improve scalability. An application of planning to real-time promising of order due dates for custom built products provides the context for empirical evaluation. Results of analytical evaluations and simulation experiments clearly demonstrate the scalability of the TB-tree relative to existing index structures in terms of both time and space.