OMSCS student here. You are absolutely right that the DB course is one of the weaker offerings. There is a newer Database System Implementation course, which is based on Andy Pavlo's excellent undergrad course (which is also available online), but only the first half or so of that course is covered, which is disappointing for a graduate course. In terms of the larger program, however, the two database courses are outliers and most courses are of much higher quality and definitely not undergrad level.
Hey — head TA of DSI here and want to correct some misconceptions.
DSI (6422) is taught by Andy Pavlo’s first PhD student who help to create the CMU course and a rather famous DB person. It is the same contents as the on-campus course (and were actually working to deepen/increase the depth of coverage). It’s designed to bridge between DB Theory and reading Postgres or MySql source code when it comes to DB designs and trade-offs — and covers topics like r-tries which I don’t think is covered elsewhere + a series of 12 seminal DB papers. As in any other grad-level class, you get out as much as you put in — and it’s super rare to have access to a DB researcher like Joy or hear his takes on DB development as a student at scale.
If anything, the feedback we’ve gotten from both on campus undergrad and MS students is that the OMSCS lectures + improvements are making their session more rigorous.