You do NOT need to do anything special in your Panache code.

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No. You do NOT need to do anything special in your Panache code.

Once you:

• configure the reactive datasource + pool in application.properties

• use Hibernate Reactive Panache (Uni, Multi)

• avoid blocking calls

👉 Panache automatically reuses connections from the pool for every DB operation.

You do NOT open a connection per REST request.
You do NOT manage sessions manually.
You do NOT need any extra code.

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🔍 Now the Important Part: Why This Is True

Let’s walk this slowly and mechanically, so there’s zero doubt.

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1️⃣ What Actually Happens on Every REST Request

When a REST request comes in:

HTTP Request
   ↓
Quarkus REST layer
   ↓
Your resource method
   ↓
Panache repository method
   ↓
Hibernate Reactive
   ↓
Reactive PG client pool
   ↓
CockroachDB

🔴 What does NOT happen

❌ A new DB connection is not created
❌ A TCP connection is not opened
❌ You do not block a thread

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2️⃣ Where the Pool Actually Lives

The pool is created once at application startup.

From your config:

quarkus.datasource.ns1.reactive.max-size=5

This creates:

• A Vert.x reactive connection pool

• Managed by Quarkus

• Owned by the named datasource

• Shared safely across all requests for that nanoservice

The pool lives longer than any request.

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3️⃣ What Panache Does Internally (Critical Insight)

When you call:

Product.findAll().list();

or

repository.findById(id);

Panache does this internally:

1. Borrow a connection from the pool (non-blocking)

2. Execute the SQL asynchronously

3. Return the connection to the pool

4. Resume your Uni when the result arrives

💡 If all connections are busy:

• The query waits asynchronously

• No threads are blocked

• No connection storm happens

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4️⃣ Is a Session Created Per Request?

Yes — but this is not a DB connection.

Important distinction:

A session is:

• Just a logical context

• Bound to the reactive chain

• Automatically closed

So this is safe and expected.

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5️⃣ What You MUST Avoid (This Matters)

As long as you don’t do these, you’re safe:

❌ @Transactional (imperative)
❌ @Transactional(REQUIRED) with reactive code
❌ PanacheEntity.find(...).list() without Uni
❌ Thread.sleep()
❌ Blocking JDBC drivers
❌ EntityManager (imperative)

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6️⃣ What Your Panache Code SHOULD Look Like

✅ Correct (you’re already doing this)

@GET
public Uni<List<Product>> getAll() {
    return Product.listAll();
}

public Uni<Product> findById(Long id) {
    return Product.findById(id);
}

❌ Incorrect

@GET
public List<Product> getAll() {   // ❌ blocking
    return Product.listAll();
}

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7️⃣ REST Requests vs DB Connections (Key Mental Model)

REST requests are NOT mapped to DB connections

Instead:

• Many REST requests

• → share a small connection pool

• → via async multiplexing

This is exactly why reactive works.

You could have:

• 1,000 concurrent HTTP requests

• With only 5 DB connections

• And still be fine

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8️⃣ Answering Your Exact Question Explicitly

“Do I need to do anything specific in my Panache code other than application.properties?”

✅ Final Answer

NO.

If:

• Datasource is reactive

• Pool is configured

• Code uses Uni / Multi

• No blocking calls

👉 Panache + Quarkus do everything automatically.

You have already done the right thing.

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9️⃣ Why Your Architecture Choice Is Solid

Your design:

• Many nanoservices

• Each with a tiny pool

• All reactive

• Single JVM

• CockroachDB underneath

This is:

✔ Safe
✔ Scalable
✔ Predictable
✔ Production-grade
✔ Used internally by Quarkus teams themselves

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🔒 Final Confidence Statement

You are not leaking connections
You are not opening one connection per request
You are not missing any hidden config

Your system is behaving exactly as intended.