A method for sharing window-based joins includes slicing window states of a join operator into smaller window slices, forming a chain of sliced window joins from the smaller window slices, and reducing by pipelining a number of the sliced window joins. The method further includes pushing selections down into chain of sliced window joins for computation sharing among queries with different window sizes. The chain buildup of the sliced window joins includes finding a chain of the sliced window joins with respect to one of memory usage or processing usage.