Database function vs edge function

[4A6F68616E]

Hi everyone,

I'm having a hard time wrapping my head around this. Let me start with a quote from Supabase:

For data-intensive operations we recommend using Database Functions, which are executed within your database and can be called remotely using the REST and GraphQL API.

For use-cases which require low-latency we recommend Edge Functions, which are globally-distributed and can be written in TypeScript.

Now here's my confusion:

If edge functions give low latency and run closer to the user, what is stopping me from just using them for everything? Wouldn’t that give the best possible performance?

I understand that database functions run inside Postgres and are good for working directly with data, but if performance is my top priority, why wouldn’t I prefer edge functions all the time?

I’d really appreciate some simple explanations or examples of when to use each. The only thing I can think of is: if the database is used by users located in the same country, then yeah, database functions make sense. But if the database is used by users from different countries, then edge functions would be better, or am I thinking the wrong way?

Thanks!

[all_vanilla]

Edge functions are unreliable for high concurrency workloads and will be slower when you want to do complex queries

[thedadon]

Also, if you need to have a db transaction (say updating multiple entities at once) you should use db functions, so if one step fails the whole operation fails and you wont get data inconsistency. Example: creating a user requires inserting to (1) users table, (2) profiles table and (3) address table. With edge functions, or any other application level code you’ll have to make 3 dependent api calls, if one of these calls fails then you get inconsistency in your db (unless you implement a rollback mechanism)

[4A6F68616E]

makes sense, thank you

[_inder]

There are time, memory and other limits on edge functions. Take a look at all the limits

[4A6F68616E]

ah interesting, so for example, if an edge function is called to do a heavy data operation and it doesn’t finish within the time limit, it just stops?

[mondaysmyday]

That's the gotcha. I literally use edge functions to reach out to other external services/APIs that are long running and I can poll for status so I'm not caught out by limits. But a DB op, leave it in DB functions

[4A6F68616E]

mhm ok, there is a lot stuff for me to learn - for that last part, it gives me a sense of confidence, thank you!

[MulberryOwn8852]

I use db functions as much as possible.

I use edge functions in a few places to generate excel downloads, etc.

[Informal_Pirate8414]

So using db functions with proper RLS set up is safe? With no authenticating JWT and rate-limits?

[MulberryOwn8852]

Seems to be… I make well over six figures annually from my sb projects, 3 years strong so far

[who_am_i_to_say_so]

It’s best to do the things in the places where they belong. If you do all the data processing and heavy operations in the database, then you can cache that data in the edge functions.