What I’ve seen done, and what I currently use are embedded arrays with node id’s in each document. So document user1 has property groups: [id1,id2] And document group1 has property users: [user1]. Document group2 also has property users: [user1]. This way you get a Group object and easily select all related users, and the same … Read more
No, there isn’t a technical reason. It’s mostly just opinion and using NoSQL with Node.js is currently a popular choice. Granted, Node’s ecosystem is largely community-driven. Everything beyond Node’s core API requires community involvement. And, certainly, people will be more likely to support what aligns with their personal preferences. But, many still use and support … Read more
I found two impressive articles about this subject. All credits to highscalability.com. The information in this answer is transcribed from these articles: 35+ Use Cases For Choosing Your Next NoSQL Database What The Heck Are You Actually Using NoSQL For? If Your Application Needs… • complex transactions because you can’t afford to lose data or … Read more
In my experience, you shouldn’t use a relational database when any one of these criteria are true: your data is structured as a hierarchy or a graph (network) of arbitrary depth, the typical access pattern emphasizes reading over writing, or there’s no requirement for ad-hoc queries. Deep hierarchies and graphs do not translate well to … Read more
There is no conclusion that composite primary keys are bad. The best practice is to have some column or columns that uniquely identify a row. But in some tables a single column is not enough by itself to uniquely identify a row. SQL (and the relational model) allows a composite primary key. It is a … Read more
You need to think of how you approach the application in a document oriented way. If you simply try to replicate how you would model the problem in an RDBMS then you will fail. There are also different trade-offs that you might want to make. ([ed: not sure how this ties into the argument but:] … Read more
The technical definition of an identifying relationship is that a child’s foreign key is part of its primary key. CREATE TABLE AuthoredBook ( author_id INT NOT NULL, book_id INT NOT NULL, PRIMARY KEY (author_id, book_id), FOREIGN KEY (author_id) REFERENCES Authors(author_id), FOREIGN KEY (book_id) REFERENCES Books(book_id) ); See? book_id is a foreign key, but it’s also … Read more
Hmm, not quite sure what your question is. In the title you ask about Databases (DB), whereas in the body of your text you ask about Database Management Systems (DBMS). The two are completely different and require different answers. A DBMS is a tool that allows you to access a DB. Other than the data … Read more
You could have a design like: +—————+ +——————-+ | PRODUCTS |—–< PRODUCT_VARIANTS | +—————+ +——————-+ | #product_id | | #product_id | | product_name | | #variant_id | +—————+ | sku_id | | +——————-+ | | +——–^——–+ +——–^——–+ | PRODUCT_OPTIONS |—–< VARIANT_VALUES | +—————–+ +—————–+ | #product_id | | #product_id | | #option_id | | #variant_id … Read more
If you’re going to be doing any syncing between databases with occasionally connected apps, then you should be using GUIDs for your primary keys. It is kind of a pain for debugging, so apart from that case I tend to stick to ints that autoincrement. Autoincrement ints should be your default, and not using them … Read more