What is the difference between scylla read path and cassandra read path?

Question

What is the difference between Scylla read path and Cassandra read path? When I stress Cassandra and Scylla then Scylla read performance poor by 5 times than Cassandra using

Answer 1

@Sateesh, I want to add to the answer by @TomerSan that both Cassandra and ScyllaDB utilize the same disk storage architecture (LSM). That means that they have relatively the same disk access patterns because the algorithms are largely the same. The LSM trees were built with the idea in mind that it is not necessary to do instant in-place updates. It consists of immutable data buckets that are large continuous pieces of data on disk. That means less random IO, more sequential IO for which the HDD works great (not counting utilized parallelism by modern database implementations).

All the above means that the difference that you see, is not induced by the difference in how those databases use a disk. It must be related to the configuration differences and what happens underneath. Maybe ScyllaDB tries to utilize more parallelism or more aggressively do compaction. It depends.

In order to be able to say anything specific, please share your tests, envs, and configurations.