No, they did not only generate tuples in-memory for SABER. From the linked Flink blog post:

> Databricks made a few modifications to the original benchmark, all of which are explained in their own post: > Removing Redis from step 5 > Generating data in memory for Flink and Spark; generating data via Spark and writing it to Kafka for Kafka Streams > Writing data out to Kafka instead of to Redis

I think the authors know that the benchmark is weak. The blog post isn't (to my reading) claiming that it is proof that SABER is great so much as that the distributed stream processors need better evidence that they should exist (vs the Databricks Structured Streaming SIGMOD 2018 paper, in which the YSB benchmark is (I think) the only quantitative evaluation they do).