That is a terrible approach. No database platform is tuned by default.
You may have to run a utility, or edit a config file, but a new system must be configured to fully utilize available hardware, and for the expected workload.
A benchmark run on default config is at best misleading - it smells like marketing spam. You actually dampen interest in a forum like this with such an approach.
Disclaimer: I'm part of the ArangoDB team. As written in the post the whole benchmark is open source. The idea is that you can run it on your own. Also, pull requests are welcome. If you think it's marketing spam, take the chance and improve the configuration. We will publish an update of the post.
Not really true any more. Many of the newer databases (e.g. Mongo) and database-like systems (e.g. Elasticsearch) try to give a good default experience.
Since I don't know about current versions of MongoDB, and am genuinely interested, how does Mongo know how much memory to use as an example?
Typically with PostgreSQL, you have to expand the defaults when running on modern server class hardware, so the engine uses enough RAM. Simply letting it use all RAM available can be problematic, since the DB engine and OS have to fight for cache, etc.
Java based systems like Elastic might still need JVM tuning, especially with a distributed platform like ES, which might be run in a large number of small machines, a smaller number of large machines, or containers.
You may have to run a utility, or edit a config file, but a new system must be configured to fully utilize available hardware, and for the expected workload.
A benchmark run on default config is at best misleading - it smells like marketing spam. You actually dampen interest in a forum like this with such an approach.