On bare-metal or base VPS servers, it's a Good Idea™ to set swappiness to 1 and have only a tiny amount of swap (say 512 MiB) in order to measure memory utilization pressure and OOM via swap usage trends in monitoring/alert tools. (Any sizable swap usage indicates heavy memory usage and likely things breaking.) Having giant swap files hides problems, slows servers and wears SSDs. Excessive memory usage is rarely addressed unless memory metrics are time-series monitored. Also, if running a production DBMS, as with most server programs, monitor major metrics from both outside of it and those metrics it offers.
