The present technology includes an optimized b-tree. To improve concurrent access, a read lock can be applied to traversed nodes of a b-tree in a lock coupling. A read locked node can be promoted to a write locked node upon a determination that the node is likely to be modified, wherein the locked node first restricts access to further functions and then applies a write lock to the node when all existing functions accessing the node end. If one of the other functions attempts to promote the later function can be canceled and removed from the tree. A node can be promoted if the node is likely to be modified when considering multiple factors such as type of function, whether it is a leaf node, the number of keys in the node, or the number of keys in a child node.