He is a genuinely helpful professor, who is always trying his best to help us learn and improve.

Professor is a very nice person, even there are quite a lot negative things you can say about this course by Rosario: 1. intensive course material, 2. hard test. I took this course with no awareness that it would be such intensive and hard almost like CS111: you have to read a lot about textbook chapter which is already an intensive workload(while eventhough it did not help a lot for the exam), each lecture slide is full of contents, really heavy, and the exam, especially final, can be said to be a nightmare if not well prepared, with even no one get an A- for the raw score.
That been said, these thing still don't negate the fact that Professor Rosario is a very nice person: he covered a lot in lecture because he did want us to learn a full image of database system, his giving hard exam seems not a real bad thing for me because it is an open book exam and indeed, after careful investment of effort you can get a really good grade for it. He tried to relieve us from too much consideration about letter grade, offering chances of enhancing the grade like replace the midterm grade with final one if you have done better in final, and even break his own originally designed grading rubric for homework to improve general grades for all. He really helped students a lot, especially in his office hour. He provide office hour almost every day during the week 10, and if you utilize them well, it will be really helpful.
He is tough and strict on rules in lecture and assignments, but it seems that he had his own ways to help students to learn without directly violate those rules. Pretty good man, if you see his last lecture slide with pages of them offering practical suggestions on both academy and industry.
Just a little post for RRR, whom I hated initially but respect at last, by all what he had done. Thanks professor:)

Took this class Spring2020 and it seemed like Rosario took a lot of feedback based on the previous negative reviews.

His tests were very fair and honestly on the easier side if you attended lecture and did the hw. He's very clear and has a good understanding of all the material so I made sure to attend all lectures.

He previously had large coding projects as a part of the class but this quarter instead chose to do smaller psets, which made the courseload very manageable.

He has good insights on the applications of databases due to his industry experience. Highly recommend you take this class with him

This class is arguably the most useful and important class that I have taken at UCLA, joint top along with CS 32. Way more than just a SQL class, Professor Rosario provides a holistic overview of the entire database system. He would often share with us his personal experiences and tips in industry, which I really appreciate since most other professors don't do that. While the first half of the class is mostly focused on SQL and Relational Algebra, the second half includes interesting topics such as Data Warehousing, Streaming Systems and NoSQL. Towards the final parts of the class, we dived even deeper into the hardware aspects, such as data storage, which felt slightly dry at times but definitely integral for those who aim to become data engineers.

Homework assignments were mostly well-crafted and fun to work on, especially Assignments 5 and 6 where we had to write queries in Spark SQL, MongoDB and Neo4j. The only downside of this class is Rosario's fast-paced lectures and tough exams. He goes at the speed of a Shinkansen during lecture, but fortunately he records them so I can re-watch to consolidate my learning. Exams are a time-crunch with never-ending questions, but each question itself is actually not too challenging as long as you are well-prepared.

I was searching for data science internships while taking CS 143, and it has been extremely helpful in tackling SQL interview questions, as well as expanding my knowledge in database systems. Now that I have secured an internship, looking back in hindsight, this class has played a pivotal role in my success. For anyone looking to enter the field of Data Science/Data Engineering/Software Engineering, I would highly recommend this class with Rosario.

Great lecturer and overall good class but bad administration. Like the content is really good. I use it in my job actually. The administration for this class was uhhhh bad. No regrade request for exams, had a really stupid note sheet policy for the midterm and just a bunch of other stupid stuff. I got a point off cause I didn’t show enough work on an assignment graded on completion. Dude also went on a whole rant about how your grade doesn’t define your worth and then proceeded to give a final with like 100 questions. Again though great lecturer and don’t regret taking the class. The grade distribution is also much better than it used to be.

He's not a bad professor, but this class has so much content it is hard to keep up. My issue is that he is often unclear about what's really important for us to learn and what will be on the exams. It makes sense that the concepts that are most important for us to know would be on the exam. However, often times he would have very minuscule facts or edge cases as questions on the exam, as a kind of "gotcha" question that would reference one line on one slide instead of a broad key concept. And in terms of helpfulness, sometimes his Piazza answers would come off as passive-aggressive as if we're coming at him and insulting his knowledge. The homework is pretty doable and sometimes fun to figure out the correct queries. This is a pretty important class for CS majors, so I would take it with Rosario and just thug it out.

Rosario has a lot of mixed reviews, and you might have similar or very different experiences to these posts. He is a rather perplexing person and goes back and forth in his demeanor. I'll first start talking about the class itself:

The lectures are extremely well put together. It is evident he has put a lot of time into refining them to be both engaging and informative, and he has a lot of examples for things like topological sort, dependencies and normal form, and many more topics. There is A LOT of information covered in this class, mostly in the second half. A lot of it was pretty useful, like learning SQL/NoSQL, transactions, and MapReduce. Some of the stuff we covered, on the other hand, seemed like just a formality and doesn't have real-world value. I recommend skimming through the lecture slides beforehand, and then reviewing a little bit after.

Assignments are, for the most part, interesting and useful, and are good prep for the exams. Some of them were graded on completion (with the caveat of showing ALL your work), and the ones that were graded on correctness usually had an autograder. Specs are somewhat clear, however, if you are unfamiliar with using the terminal (which some people might be if you aren't a CS major), then a couple of the homeworks would be a nightmare.

The exams, however, are really hard. The midterm was not too bad in difficulty, but the grading Rosario used was absolutely ridiculous. You could write a full query that makes sense, and still get 0/18 points because you were missing one thing. The final was hands down the hardest final I've taken at UCLA and most of it was not reflective of what we learned in the class. It stresses a lot of SQL, so you better know how to write good queries going into it. He does grade on a curve, but still it's crazy how much the final was. Multiple people didn't even finish it.

Now I'll talk about Rosario as a professor. He does seem to care about student's in some capacity. He will answer every question in lecture and is pretty approachable in office hours. He is also very active on Piazza and will answer questions with mostly good clarity. He's also understanding when it comes to being a student. However, he can be pretty mean sometimes. There were instances on Piazza when he was rude and unhelpful, and in person he will become extremely defensive when you question his grading, almost to the point of being unprofessional. Yeah, I can understand being dumbfounded when people don't fill in the bubbles on the multiple choice part of the exam even after he talked about it multiple times (I mean it's not that hard to just follow directions), but there's no need to become abrasive when students become worried about their grade. We're all just trying to get by.

TLDR; this class is interesting and useful. Exams are unfair and grading is ridiculously strict, but his curve seems to make up for it. Rosario is for the most part a nice dude, and for the most part is a changed man from the previous reviews, but his old side seems to slip out here and there. If you're looking for an easy elective, this class is not it. Side note: Rosario is seriously accomplished as a person which is insanely impressive.

Class itself is great if you don't have to interact with the professor - he himself is extremely closed-minded and will not tolerate anything that contradicts his beliefs. Examples: no regrade requests allowed at all, extremely harsh grading rubrics on exams where missing a tiny amount of a large problem would cause massive point deductions, and forced the TAs to revert a regrade request giving back points for a problem that was solved correctly.

Ryan sucks. Don't believe all the recent reviews saying he's a "changed man." While he comes off as super friendly and helpful during lecture (he loves to stress how "your mental health as a student is important"), he DOES NOT CARE ABOUT YOU. He obviously has some sort of psychological disorder that causes him to be hyper aggressive towards anyone who questions his authority. I witnessed him behave extremely unprofessionally towards students in the class because he was power tripping. The class also just straight up sucks, the first half is fine but the second half starts delving into information sludge that doesn't even seem helpful at all. The final exam was also the most absurd thing I have ever taken.
My analysis is this: Ryan was bullied as a child (because he is 3 foot 9 and looks like a troll), and now desperately grasps ahold of any modicum of power that this class gives him.

His organization for each lecture is absolutely incredible. Each set of slides is always posted beforehand, recordings are uploaded, and notes are always posted afterwards. Should any student feel unconfident about information that is covred in class, it is so easy to go back and re-watch anything or look at the many resources posted to understand. Rosario also works closely with his TAs and creates really intentional homeworks, which makes the learning experience for this class so much better. I do think he lectures a little bit too fast and covers too much information, kind of expecting studetns to get it on the first time he mentioned it if he says it just once. It seems that he really understands students in a refreshing way that isn't seen with most other professors, however his teaching style definitely caters towards the type of people who hear one thing once and remember it completely making it kind of hard to keep up. That being said, this class isnt meant to be easy, and I think thats really clear -- you can still learn a lot even if you perform well. The other thing is that he is a really strict grader ... for someone who seems to try and come off as understanding to students his strict policies on regrades and grading in general kind of distance this idea that he cares about his students.