Materialize Window Functions

For window functions, when an input record in a partition (as determined by the PARTITION BY clause of your window function) is added/removed/changed, Materialize recomputes the results for the entire window partition. This means that when a new batch of input data arrives (that is, every second), **the amount of computation performed is proportional to the total size of the touched partitions**. For example, assume that in a given second, 20 input records change, and these records belong to **10** different partitions, where the average size of each partition is **100**. Then, amount of work to perform is proportional to computing the window function results for **10*100=1000** rows. To avoid performance issues that may arise as the number of records grows, consider rewriting your query to use idiomatic Materialize SQL instead of window functions. If your query cannot be rewritten without the window functions and the performance of window functions is insufficient for your use case, please contact our team.