"They all have trade-offs. Key-value stores eliminate your ability to access data by anything other than its key. So, you have an article with an id of 5. What

"They all have trade-offs. Key-value stores eliminate your ability to access data by anything other than its key. So, you have an article with an id of 5. What if you want to look up the articles by author 9" You build and maintain indexes, just like you do with an SQL db.