When I upgrade to 3.3.5 version of ArangoDB, there is the following warning
2018-05-24T10:25:32Z [26942] WARNING {memory} maximum number of memory mappings per process is 65530, which seems too low. it is recommended to set it to at least 512000
2018-05-24T10:25:32Z [26942] WARNING {memory} execute 'sudo sysctl -w "vm.max_map_count=512000"'
Is it safe to tinker with the system setting (as I understand it)? And what is the meaning of increasing the max_map_count toArangoDb in particular?
It is safe to increase this value. It allows applications to allocate more RAM. The preset value on different distributions are sane values for user interaction. However, when you operate inherently memory-heavy applications like databases, you might have to relax such limits to your needs. Having said that, if you have a malicious program on your system, it also is allowed to allocate more memory.
But let's not forget, that the warning is only a warning. So for as long as your database is not huge, you are not working with lots of open cursors you and don't experience any performance issues, you might not have to make any changes for now. Just keep it in the back of your head, so that you know, what to tweak, when suddenly performance goes down.
Also, the MMFile storage engine is more affected than the RocksDB engine.
