Mostafa Mokhtar, et al, have a comparison of Apache Impala to Amazon Redshift:
For this analysis, we used TPC-DS on a 3TB dataset and selected 70 out of 99 the queries that run without any modifications or uses variants on both Redshift and Impala. We wanted to use a larger dataset (similar to what we’ve used in previous benchmarks), but due to Redshift’s data load times, we had to reduce the data size. (Note: This benchmark is derived from the TPC-DS benchmark and, as such, is not directly comparable to published TPC-DS results.)
This is coming from one of the two vendors, so take it with however many grains of salt you’d like.