Described herein is a computer implemented method for inserting a new item to a tree-structured dataset. The method comprises: calculating a new item data summary; generating a new leaf node for storing the new item and the new item data summary; adding the new leaf node to the dataset; and recalculating data summaries for all internal dataset nodes in an update path starting at a parent of the new leaf node and ending at a root node of the dataset. The data summary for a given internal node in the update path is calculated based on data summaries for each of the given internal node's children nodes.