Hello prisma team! Have a question with respect to prisma connections. How does prisma fetch a connection from connection pool? Context - I am using Postgres as DB and turned logging on. So in the following code snippet, prisma is fetching two connections from pool.

// Node js
// Fetched a connection from pool. --> (1)
const firstQuery = await prisma.model.find();
// Fetched a connection from pool. --> (2)
const secondQuery = await prisma.model.find();

So

1

and

2

statements are logged while calling these queries. Can you explain why second statement is logged? Prisma should use the same connection (connection used for performing first query), right?

Does it indeed use two different connections?

So how I can be sure about this like whether it is opening two different connections or same connections? And if yes where I have to look i.e in Prisma client or in DB?

I would look at the database log to see if multiple connections are opened or not

Ok sure, I will then log enable db logs, and check, thanks for clearing out this!

Prisma is the connection pool.

Hey yes that explains a lot, is there a way we can log these details? Reason - we want to debug an issue on our production app. We have turned on logging, but we weren't able to reproduce the bug consistently. Bug is basically we are running two queries one after another, if both the queries use same connection then its working correctly but if the latter query use another connection we will get an error.

Why is that? Does the query rely on the previous one setting some state in the connection?

So with first query we are creating

temporary_table

, with second we are inserting into the

temporary_table

. Temporary tables in postgres remains per session (don't know how sessions are managed in Prisma i.e if session can have multiple connections or not). So kind of second state is dependent on first state.

If so, Prisma generally gives no guarantees on the connections. Even if you get the same one, it could actually be a load balancer or pooler (e.g. PgBouncer) that uses two different database connections

Yeah wrapping in a transaction makes sense. https://prisma.slack.com/archives/CA491RJH0/p1623081093137000?thread_ts=1622831239.062200&cid=CA491RJH0 So while picking a connection does it have any id or something for differentiating between the connections?

No, we are not exposing that in the logging yet as this is an internal implementation detail.

Thank you so much for this detailed explanation, will try using transactions for the queries.