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I love postgres json aggregates, but since postgres cant do nested aggregates it is kinda limiting when I would like to build my whole query response in a singl

I love postgres json aggregates, but since postgres cant do nested aggregates it is kinda limiting when I would like to build my whole query response in a single postgres query

twojacobtwo 3y ago
I'm new to web-dev (and databases), so my apologies for the potentially silly question, but what's an example situation where you would use nested aggregates and what kind of effort would it save, if it were possible?
- 5636588 3y ago
  Was curious myself so asked chatgpt and this what I got: Nested aggregates in databases are useful when you want to perform calculations or summaries on groups of data within larger groups. For example, imagine you have a database of sales transactions with products and categories. You could use nested aggregates to find the total sales for each category and then calculate the average sales per category. It saves effort by allowing you to perform calculations at different levels of granularity in a single query.
  - sargstuff 3y ago
    goal directed programming is the related non-sql programming paradigm. unicorn/icon[1] ---- Use cases:[2] autoparts inventory (book keeping page statics of sales/sales person, parts, inventory on hand, etc) internet statistics for through put on all interfaces on group of servers [0] --- topic related books: Joe Celko has book series 'SQL for Smarties' that covers basic through advanced aggrecation with sql using example queries. Joe Celko's 'Trees and Hierarchies in SQL for Smarties' covers some of the ideas related to 'SQL statment returned a database'? --- [0]: https://dba.stackexchange.com/questions/173044/nested-aggregate-functions-over-different-dimensions https://dba.stackexchange.com/questions/173044/nested-aggreg... [1] : http://unicon.org/ http://unicon.org/ [2] : https://cs.uwaterloo.ca/~tozsu/courses/CS338/lectures/6%20Nested%20SQL.pdf https://cs.uwaterloo.ca/~tozsu/courses/CS338/lectures/6%20Ne...
- eddd-ddde 3y ago
  Personally, I prefer raw sql over something like an ORM. So many times I want to get all users, with all posts, with all post comments (example). You can do an array aggregate to get all users and their posts in the array, with build_jsonb_object you can make the posts an object of say id and content. But then you can't really make another array aggregate per post.
sargstuff 3y ago
Can fake it with postgress copy/execute[0], where each aggregate block level is a transaction. [0] : https://medium.com/r3d-buck3t/command-execution-with-postgresql-copy-command-a79aef9c2767 https://medium.com/r3d-buck3t/command-execution-with-postgre...
sargstuff 3y ago
shell out for nested aggregates[0]. one 'sql querry' to run a batch shell containing all multiple aggregate levels in a file, import back in to return table reference. [0] : https://medium.com/r3d-buck3t/command-execution-with-postgresql-copy-command-a79aef9c2767 https://medium.com/r3d-buck3t/command-execution-with-postgre...
klysm 3y ago
You can do nested aggregates though unless I’m misunderstanding what you mean by nested aggregate

I love postgres json aggregates, but since postgres cant do nested aggregates it is kinda limiting when I would like to build my whole query response in a single postgres query

twojacobtwo 3y ago

I'm new to web-dev (and databases), so my apologies for the potentially silly question, but what's an example situation where you would use nested aggregates and what kind of effort would it save, if it were possible?

5636588 3y ago
Was curious myself so asked chatgpt and this what I got: Nested aggregates in databases are useful when you want to perform calculations or summaries on groups of data within larger groups. For example, imagine you have a database of sales transactions with products and categories. You could use nested aggregates to find the total sales for each category and then calculate the average sales per category. It saves effort by allowing you to perform calculations at different levels of granularity in a single query.
- sargstuff 3y ago
  goal directed programming is the related non-sql programming paradigm. unicorn/icon[1] ---- Use cases:[2] autoparts inventory (book keeping page statics of sales/sales person, parts, inventory on hand, etc) internet statistics for through put on all interfaces on group of servers [0] --- topic related books: Joe Celko has book series 'SQL for Smarties' that covers basic through advanced aggrecation with sql using example queries. Joe Celko's 'Trees and Hierarchies in SQL for Smarties' covers some of the ideas related to 'SQL statment returned a database'? --- [0]: https://dba.stackexchange.com/questions/173044/nested-aggregate-functions-over-different-dimensions https://dba.stackexchange.com/questions/173044/nested-aggreg... [1] : http://unicon.org/ http://unicon.org/ [2] : https://cs.uwaterloo.ca/~tozsu/courses/CS338/lectures/6%20Nested%20SQL.pdf https://cs.uwaterloo.ca/~tozsu/courses/CS338/lectures/6%20Ne...
eddd-ddde 3y ago
Personally, I prefer raw sql over something like an ORM. So many times I want to get all users, with all posts, with all post comments (example). You can do an array aggregate to get all users and their posts in the array, with build_jsonb_object you can make the posts an object of say id and content. But then you can't really make another array aggregate per post.

sargstuff 3y ago

Can fake it with postgress copy/execute[0], where each aggregate block level is a transaction. [0] : https://medium.com/r3d-buck3t/command-execution-with-postgresql-copy-command-a79aef9c2767 https://medium.com/r3d-buck3t/command-execution-with-postgre...

sargstuff 3y ago

shell out for nested aggregates[0]. one 'sql querry' to run a batch shell containing all multiple aggregate levels in a file, import back in to return table reference. [0] : https://medium.com/r3d-buck3t/command-execution-with-postgresql-copy-command-a79aef9c2767 https://medium.com/r3d-buck3t/command-execution-with-postgre...

klysm 3y ago

You can do nested aggregates though unless I’m misunderstanding what you mean by nested aggregate