“PG writes out and syncs the accumulated WAL (= Transaction log) records at each transaction commit [snip] It also syncs at the end of each WAL file (16MB by default). The wal_writer process also wakes up occasionally and writes out and syncs the WAL.“

So PG keeps data consistent by default - unlike MongoDB.

> MySQL and PG are not truly consistent per default, they don't fsync every writes. MongoDB explains that pretty well [links]

Where in those MongoDB doc links is there anything about MySQL or PG?