Provided are techniques for processing window partitioning and ordering for OLAP functions. A prior compare operation is performed by: receiving an input vector for each of one or more attributes of input data that represent one of a partition-by column and an order-by column in a database query; generating a per-attribute comparison vector for each input vector; and producing a single output vector using each per-attribute comparison vector, wherein each value of the single output vector is a Boolean attribute whose value for a given tuple is true if a current value and a most recent prior value of any of the one or more attributes are different.