typically the advantages of nosql are along the lines of schema-less, speed of writes, reads should be faster typically as well. speed of writes, there are no

typically the advantages of nosql are along the lines of schema-less, speed of writes, reads should be faster typically as well. speed of writes, there are no constraints that need to be checked with nosql (typically), it's like writing a value into a hash map. with sql there needs to be a check for multiple constraints: uniqueness, null, datatype, etc. if there's a relation then it needs to check those constraints as well. the whole thing about rdb's is that they're trying to normalize data where possible, you deal with id's and the fields of the table can change without you needing to propagate these changes to other places. in nosql, if you have relational data then you have to manually make sure all these changes are propagated, pretty annoying if you ask me and quite error prone, you end up writing logic an rdb already optimizes for you. take "cascaded deletes", too, this is manual in nosql. the best usage of nosql is if you have stagnant data, and you need to write it quickly, take a log file contents, for example, or if your data consistency requirement is not that critical (let's say you implement likes for a web post system, if you're missing 300 here or there, not a huge deal). other cases are things like counters, if you have a game where you're tracking scores, things are changing rapidly , but there's really not a lot of relation with other data, redis is a great example of this type of nosql storage, built in incrementing counters. most of the time when someone brings up nosql for an application, my initial reaction is that it's a premature optimization, for a lot of data, there are tight relationships and rdb is great for that. but i tend to see that you need both in many cases.