Sorry if there's already an answer for this, I searched for it and I didn't find exactly my scenario.
Once again is a question like "What is the fastest/best performance DB?". But since the answer depends on the scenario, my scenario is this: I want to write many logs to DB, thousands per second. But I will not read them often. Indeed 99,99% of them will never be read again, but once in a while I will need to read. Schema is not complex, just key/value. Once in a while I will read by value and I will not care at all if this read takes minutes. The correctness of the read will be critical, but not the performance.
So far it seems the best solutions are things like MongoDB, Cassandra... and perhaps the best DynamoDB?