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>That's one way of writing a web service. It's not the only or even "normal" way - IME it's much more common to have the database act as a dumb CRUD key/value s

>That's one way of writing a web service. It's not the only or even "normal" way - IME it's much more common to have the database act as a dumb CRUD key/value store, and put logic in the application layer (indeed many web services use a pure key/value store rather than a "database" as such). Wrong. The normal way is SQL. Web applications are suppose to be written in ways as nonblocking as possible. As much logic that can be pushed to the database as possible. That is the way to go. This reduces round trip time by a huge amount. The pure key/value store is non-standard, but it is a way to do it. Not the traditional way and not the majority way either. Many of the major web application frameworks assume SQL as the underlying database not mongo or some other key value db. >You're right that if your logic is in the database, and it's an ACID-style "mutate the current state of the world" database then you can't really use pure functional techniques. The only solution to that is to not do that. Not only am I right. It's the main way things are done on the web. The functional layer is largely just code generation: Pure Functions with http requests as input and SQL code as output. This is the core model.

lmm 3y ago
> Wrong. The normal way is SQL. The normal way is SQL. Web applications are suppose to be written in ways as nonblocking as possible. As much logic that can be pushed to the database as possible. That is the way to go. This reduces round trip time by a huge amount. No it isn't. Most popular web frameworks expect to be used with an ORM and will autogenerate CRUD queries, while providing minimal if any support for more complex queries with logic in them. > Many of the major web application frameworks assume SQL as the underlying database not mongo or some other key value db. They do, but they use those SQL databases like a key value store - read/write by primary key most of the time, with occasional relationships but nothing fancier than that (e.g. no aggregations).
- corethree 3y ago
  >No it isn't. Most popular web frameworks expect to be used with an ORM and will autogenerate CRUD queries, while providing minimal if any support for more complex queries with logic in them. Or a query builder. Whether you use the ORM or query builder to build the queries or you manual build it is up to you. That's exactly my point. These queries aren't "autogenerated" you're writing a query in your web application with primitives decided by the framework and the ORM and then it's getting compiled into a SQL query with SQL primitives that's it. It's the same thing. I don't know what you're negating here, you're basically regurgitating exactly what I said. >They do, but they use those SQL databases like a key value store - read/write by primary key most of the time, with occasional relationships but nothing fancier than that (e.g. no aggregations). Wrong. A SQL database is more like an array. Things are stored in memory one after the other. That is the default. You can then choose an index, and have pointers to sections of the array that can make it havethe speed of your typical hash map or n-ary search tree. There is a huge amount of logic being thrown into IO.
  - lmm 3y ago
    > I don't know what you're negating here You said "As much logic that can be pushed to the database as possible" and that's simply not true. The normal, mainstream way (like it or not) is to use the database as a dumb store and have the business logic in the application layer. > A SQL database is more like an array. Things are stored in memory one after the other. That is the default. You can then choose an index, and have pointers to sections of the array that can make it havethe speed of your typical hash map or n-ary search tree. There is a huge amount of logic being thrown into IO. None of that is business logic. It's implementation details at best.
    - corethree 3y ago
      >You said "As much logic that can be pushed to the database as possible" and that's simply not true. The normal, mainstream way (like it or not) is to use the database as a dumb store and have the business logic in the application layer. False. What I said is true. As much as possible is 100% true. There are some things that have to live in the business layer. But as much as possible should be pushed to the database. All the "business layer" does is build the correct query. What you're describing is multiple queries The web application has to fetch data, do "business logic" then fetch or update data again. That is both slow and inefficient, but sometimes necessary. As much as possible the web application needs to build the query and do everything in a single IO call. The round trip time and even simply initializing multiple queries on the database side is magnitudes slower then one query that does the full operation. Business logic should be extremely thin. This idea of a dumbstore is highly misguided. No framework works like this. The database is the workhorse of the basic web application, the application layer is suppose to be the thinnest layer. Your ORM, query builder or SQL code is where most of the logic real should lie. >None of that is business logic. It's implementation details at best. False again. The basic SQL query is this: SELECT <COLUMNS> FROM <TABLE> that is list retrieval at an API level and Not just implementation details. A key value store looks like this: VALUE = MAP[KEY] Understand? There is no equivalent of key value fetching in SQL, you basically have to filter that list with SELECT * FROM TABLE WHERE id = ... You can imitate a key value store both at the implementation level and at the API level if you use a hash index on a unique id like in the example query I just mentioned, but that is not the primary mode of the SQL api. I don't think you get it.

lmm 3y ago

> Wrong. The normal way is SQL. The normal way is SQL. Web applications are suppose to be written in ways as nonblocking as possible. As much logic that can be pushed to the database as possible. That is the way to go. This reduces round trip time by a huge amount. No it isn't. Most popular web frameworks expect to be used with an ORM and will autogenerate CRUD queries, while providing minimal if any support for more complex queries with logic in them. > Many of the major web application frameworks assume SQL as the underlying database not mongo or some other key value db. They do, but they use those SQL databases like a key value store - read/write by primary key most of the time, with occasional relationships but nothing fancier than that (e.g. no aggregations).

corethree 3y ago
>No it isn't. Most popular web frameworks expect to be used with an ORM and will autogenerate CRUD queries, while providing minimal if any support for more complex queries with logic in them. Or a query builder. Whether you use the ORM or query builder to build the queries or you manual build it is up to you. That's exactly my point. These queries aren't "autogenerated" you're writing a query in your web application with primitives decided by the framework and the ORM and then it's getting compiled into a SQL query with SQL primitives that's it. It's the same thing. I don't know what you're negating here, you're basically regurgitating exactly what I said. >They do, but they use those SQL databases like a key value store - read/write by primary key most of the time, with occasional relationships but nothing fancier than that (e.g. no aggregations). Wrong. A SQL database is more like an array. Things are stored in memory one after the other. That is the default. You can then choose an index, and have pointers to sections of the array that can make it havethe speed of your typical hash map or n-ary search tree. There is a huge amount of logic being thrown into IO.
- lmm 3y ago
  > I don't know what you're negating here You said "As much logic that can be pushed to the database as possible" and that's simply not true. The normal, mainstream way (like it or not) is to use the database as a dumb store and have the business logic in the application layer. > A SQL database is more like an array. Things are stored in memory one after the other. That is the default. You can then choose an index, and have pointers to sections of the array that can make it havethe speed of your typical hash map or n-ary search tree. There is a huge amount of logic being thrown into IO. None of that is business logic. It's implementation details at best.
  - corethree 3y ago
    >You said "As much logic that can be pushed to the database as possible" and that's simply not true. The normal, mainstream way (like it or not) is to use the database as a dumb store and have the business logic in the application layer. False. What I said is true. As much as possible is 100% true. There are some things that have to live in the business layer. But as much as possible should be pushed to the database. All the "business layer" does is build the correct query. What you're describing is multiple queries The web application has to fetch data, do "business logic" then fetch or update data again. That is both slow and inefficient, but sometimes necessary. As much as possible the web application needs to build the query and do everything in a single IO call. The round trip time and even simply initializing multiple queries on the database side is magnitudes slower then one query that does the full operation. Business logic should be extremely thin. This idea of a dumbstore is highly misguided. No framework works like this. The database is the workhorse of the basic web application, the application layer is suppose to be the thinnest layer. Your ORM, query builder or SQL code is where most of the logic real should lie. >None of that is business logic. It's implementation details at best. False again. The basic SQL query is this: SELECT <COLUMNS> FROM <TABLE> that is list retrieval at an API level and Not just implementation details. A key value store looks like this: VALUE = MAP[KEY] Understand? There is no equivalent of key value fetching in SQL, you basically have to filter that list with SELECT * FROM TABLE WHERE id = ... You can imitate a key value store both at the implementation level and at the API level if you use a hash index on a unique id like in the example query I just mentioned, but that is not the primary mode of the SQL api. I don't think you get it.