Supabase is an open source Firebase alternative. Start your project with a Postgres database, Authentication, instant APIs, Edge Functions, Realtime subscriptions, and Storage.

Supabase

so do i query each time from the original db or do i just make another db like top 100 ideas under each topic and every 15 mins just update that db based on the current position of our posts?

I'm going to assume this is what your question is about, you would only need 1 database, but can have multiple tables to handle this or just do it from the one table. This is a design decision that you will have to make, if the query will be a complex on you can also look into creating a View instead of a new table and query that.

The query will be mostly to retieve posts with topic ="some specific topic" ordered by Views

And some of the times user specific like someone i am following has released a new post then i would love to do that

Same as before it will be a design decision that you will need to make, Postgres (Supabase in turn) has the options I stated above to handle whichever decision you choose.

And I wanted to ask how mature the supabase sdk for dart is?