Are transactions done in a single round trip?

[Nick-Mazuk]

Are transactions done in a single round trip? If so, how is it possible to execute arbitrary JavaScript in a transaction?

While I can map most of Drizzle ORM to SQL in my head, I can't figure out how transactions work. Mainly, I'm concerned about latency if transactions are done in multiple round trips to the database.

Consider this example from the docs:

const db = drizzle(...)
 
await db.transaction(async (tx) => {
  const [account] = await tx.select({ balance: accounts.balance }).from(accounts).where(eq(users.name, 'Dan'));
  if (account.balance < 100) { // random JavaScript execution???
    await tx.rollback()
    return
  }
 
  await tx.update(accounts).set({ balance: sql`${accounts.balance} - 100.00` }).where(eq(users.name, 'Dan'));
  await tx.update(accounts).set({ balance: sql`${accounts.balance} + 100.00` }).where(eq(users.name, 'Andrew'));
});

It looks like we can do arbitrary JavaScript in the middle of a transaction. So my assumption is that here at least three requests are made to the database:

1. The first select
2. The first update
3. The second update

…and possibly two more to start and end the transaction.

I can imagine this being really slow for more complex transactions.

[AndriiSherman]

Exactly. Transactions are separate statements with BEGIN, COMMIT, ROLLBACK statements sent to a database

For HTTP-based drivers we are going to implement batch API to reduce roundtrips to the database

[Nick-Mazuk]

Any ETA on the batch API?

[Nick-Mazuk]

Here's the batch API tracking bug: #804

Just FYI for anyone reading this in the future.