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The trouble with SQL is that it is designed around the idea of being able to execute many queries without any overhead. No problem when you are within the confi

The trouble with SQL is that it is designed around the idea of being able to execute many queries without any overhead. No problem when you are within the confines of local memory. Manageable when you are in a well connected datacenter. But you will quickly find yourself in a world of hurt when you have clients on flaky, high latency mobile connections. Okay, so now you find some way to bundle many queries, with allowances for connecting the result of one query to another, into a single request with all the results in a single response. Congratulations, you just recreated GraphQL.

valenterry 3y ago
I can't follow. I'm very familiar with both SQL and GraphQL. But SQL is strictly more powerful. If you want, you can extend the API to let the caller use with-statements, which allows to aggregate all necessary data within the same SQL query and being returned as a single response. No disadvantage to GraphQL here. I'm not saying that I suggest to do that, but for the specific point that you mention, I don't see any theoretical advantage of GraphQL in terms of performance.
- deleted 3y ago
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- randomdata 3y ago
  > But SQL is strictly more powerful. I'm not sure I understand. GraphQL doesn't need to be, nor is it meant to be, powerful. Its only purpose in life is to roll up multiple actions into a single response made from a single request. It was originally designed for those actions to be REST/RPC endpoints, but if you have an SQL API endpoint the same applies. SQL as an API isn't some novel thing. Your DBMS already does exactly that! We've been using SQL as an API for 50-some-odd years and will probably still be using it for APIs in 50 more. But, there is good reason why we have added layers on top in the datacenter. Don't expect SQL to be a suitable API for the entire world to use. > which allows to aggregate all necessary data within the same SQL query and being returned as a single response. If you push SQL to really pained lengths it can be done, but with a whole lot of added overhead elsewhere. There is no free lunch. Best to leave SQL to the job it was designed for; the job it is good at. It's okay to let it have help.
  - valenterry 3y ago
    > Yes, if you push SQL to really pained lengths it can be done, but with a whole lot of added overhead that isn't necessary. I still don't get your point. Maybe a conrete example helps: listing the contents of a user's posts. In graphql: users(id: "x") { postIds # don't really need those posts { text } } Here, if this is stored in SQL, there will probably be 3 tables: users, userposts and posts. All conntected by the respective postId. GraphQL is nice here, because instead of making a query to get the user's postIds and then one ore more queries to get each post's content, with GraphQL we only need one network trip. If the backend is half stupid, it will run 2 SQLs here. If it's smart, it will resolve the whole thing with one join. So far there is no performance benefit over writing a single SQL with a join and having the backend execute it directly. Still, I want to emphasize that I'm not advocating to do the latter - it has various drawbacks. But just im terms of performance, there is no disadvantage for the SQL solution. Even if we look at running 2 completely different semantical queries in the same graphql request, we can do the same in SQL with a width-clause. With the technique shown in the article, it's really easy to support that in the API.
    - randomdata 3y ago
      > If it's smart, it will resolve the whole thing with one join. Yes, as a practical engineer that is what you would do to deal with the overhead you have encountered in the datacenter, but you would realize that you are abusing SQL to hack around overhead issues. That is not what you would do in a less constrained environment. Logically, users and posts are distinct relations as it pertains to that example. They have no business being joined here. There is a place for joins, but that's not it. So already, for the simplest case imaginable, you are using SQL outside of the way it was designed to be used. Which is fine if it gets the job done. Purity can step to the side for the sake of engineering, of course. We are not purists here. But as the complexity ramps up, there will be a point where it stops being a decent tradeoff and enters a point of being ridiculous – where you've ended up recreating GraphQL... but poorly.
      - valenterry 3y ago

valenterry 3y ago

I can't follow. I'm very familiar with both SQL and GraphQL. But SQL is strictly more powerful. If you want, you can extend the API to let the caller use with-statements, which allows to aggregate all necessary data within the same SQL query and being returned as a single response. No disadvantage to GraphQL here. I'm not saying that I suggest to do that, but for the specific point that you mention, I don't see any theoretical advantage of GraphQL in terms of performance.

deleted 3y ago
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randomdata 3y ago
> But SQL is strictly more powerful. I'm not sure I understand. GraphQL doesn't need to be, nor is it meant to be, powerful. Its only purpose in life is to roll up multiple actions into a single response made from a single request. It was originally designed for those actions to be REST/RPC endpoints, but if you have an SQL API endpoint the same applies. SQL as an API isn't some novel thing. Your DBMS already does exactly that! We've been using SQL as an API for 50-some-odd years and will probably still be using it for APIs in 50 more. But, there is good reason why we have added layers on top in the datacenter. Don't expect SQL to be a suitable API for the entire world to use. > which allows to aggregate all necessary data within the same SQL query and being returned as a single response. If you push SQL to really pained lengths it can be done, but with a whole lot of added overhead elsewhere. There is no free lunch. Best to leave SQL to the job it was designed for; the job it is good at. It's okay to let it have help.
- valenterry 3y ago
  > Yes, if you push SQL to really pained lengths it can be done, but with a whole lot of added overhead that isn't necessary. I still don't get your point. Maybe a conrete example helps: listing the contents of a user's posts. In graphql: users(id: "x") { postIds # don't really need those posts { text } } Here, if this is stored in SQL, there will probably be 3 tables: users, userposts and posts. All conntected by the respective postId. GraphQL is nice here, because instead of making a query to get the user's postIds and then one ore more queries to get each post's content, with GraphQL we only need one network trip. If the backend is half stupid, it will run 2 SQLs here. If it's smart, it will resolve the whole thing with one join. So far there is no performance benefit over writing a single SQL with a join and having the backend execute it directly. Still, I want to emphasize that I'm not advocating to do the latter - it has various drawbacks. But just im terms of performance, there is no disadvantage for the SQL solution. Even if we look at running 2 completely different semantical queries in the same graphql request, we can do the same in SQL with a width-clause. With the technique shown in the article, it's really easy to support that in the API.
  - randomdata 3y ago
    > If it's smart, it will resolve the whole thing with one join. Yes, as a practical engineer that is what you would do to deal with the overhead you have encountered in the datacenter, but you would realize that you are abusing SQL to hack around overhead issues. That is not what you would do in a less constrained environment. Logically, users and posts are distinct relations as it pertains to that example. They have no business being joined here. There is a place for joins, but that's not it. So already, for the simplest case imaginable, you are using SQL outside of the way it was designed to be used. Which is fine if it gets the job done. Purity can step to the side for the sake of engineering, of course. We are not purists here. But as the complexity ramps up, there will be a point where it stops being a decent tradeoff and enters a point of being ridiculous – where you've ended up recreating GraphQL... but poorly.
    - valenterry 3y ago