I usually cross the line and post about RDBMS when there are interesting things that can be learned. Robert Hass explains some PostgreSQL knobs that can be turned to make things faster. But more interesting is what these knobs are doing: some are disabling fsync, others are disabling the write-ahead-log, others are making the commits asynchronous. Even more interesting is that all these knobs are in the end trading off durability for speed.
via NoSQL databases