Transaction doesn't support Promise.all

This works:

 await db.transaction(async (tx) => {
        await tx.insert...
        await tx.insert...
      });

 await db.transaction(async (tx) => {
        await tx.insert...
        await tx.insert...
      });

This does not:

 await db.transaction(async (tx) => {
        const p0 = tx.insert...
        const p1 = tx.insert...
        await Promise.all([
          p0,
          p1,
        ]);
      });

 await db.transaction(async (tx) => {
        const p0 = tx.insert...
        const p1 = tx.insert...
        await Promise.all([
          p0,
          p1,
        ]);
      });

44 Replies

Angelelz•10mo ago

There is no benefit in doing it in a promise.all. You can't insert values at the same time, that's the reason you have you use a transaction, because database operations are sequencial

shikishikichangchang•10mo ago

The two statements are for two tables. Is there a reason why they can't be executd in parallel? Yes they're part of one transaction, but I'd imageine the statemnets get executed in parallel, and if no errors occured, the transaction is completed. Else, rollback.

Angelelz•10mo ago

Have you tried this?

 await db.transaction(async (tx) => {
        const p0 = tx.insert...
        const p1 = tx.insert...
        await Promise.all([
          await p0,
          await p1,
        ]);
      });

 await db.transaction(async (tx) => {
        const p0 = tx.insert...
        const p1 = tx.insert...
        await Promise.all([
          await p0,
          await p1,
        ]);
      });

Now, the limitation is in the database itself. A transaction is designed so that the operations performed are sequential, because if you're using a transaction each operation is supposed to depend on the operation before it If you don't have that requirement, then you don't need a transaction In your case, it looks like you'd want to do it in a transaction anyway, just in case one of the inserts fails, the other will fail as well

predragnikolic•10mo ago

Not necessarily Drizzle related, but rather how JavaScript Promise.all behaves, for more info see this thread(from TypeOrm) https://github.com/typeorm/typeorm/issues/1014#issuecomment-336397434

GitHub

Transaction doesn't rollback · Issue #1014 · typeorm/typeorm

Version: 0.0.11 The "Database entity is not set for the given subject" error does not rollback transactions // this will remove row with id 1 but not id 2 repository.transaction(async rep...

sakura•10mo ago

Having this same issue, are you using mysql/planetscale? This worked fine for me with postgres

shikishikichangchang•10mo ago

I don't see how that's helpful/different from

 await db.transaction(async (tx) => {
        await tx.insert...
        await tx.insert...
      });

 await db.transaction(async (tx) => {
        await tx.insert...
        await tx.insert...
      });

Angelelz•10mo ago

Because all the query builder implement a lazy promise

Luxaritas•10mo ago

The promise.all is doing nothing in your case though Angelelz What you'd be passing are the resolved promise values

shikishikichangchang•10mo ago

"because if you're using a transaction each operation is supposed to depend on the operation before it" This is simply not true. Imagine you have a user account table and a profile info table and when ther user deletes their account you wanna delete both. The operations are independent but you definitely want them both in the same transaction Likle Luxaritas said, the promise.all doesn't do anything in your code

Angelelz•10mo ago

I don't know how the lazy promises would work in a promise.all then But my suspicion is that's probably why it's not working how you want it That's the usual purpose of using a transaction anyway

shikishikichangchang•10mo ago

Transactions are used to represent a single logical unit of work, not for dependent operations although the latter usually represents itself as the former say if I transfer money from account A to B. I need to increment B and decrement A. These two operations are not necessarily dependent (incrementing one number is independent of decrementing the other), but they need to happen "as a whole". Hence, the use of transactions

Angelelz•10mo ago

Yeah but can you parallelize them?

Luxaritas•10mo ago

Luxaritas•10mo ago

Once you pass them to Promise.all, they will all evaluate, since Promise.all is implicitly calling the then method on the promises passed in, which is what Drizzle uses to trigger the actual evaluation I am in agreement with @shikishikichangchang here - it is completely reasonable to want to use a transaction as a means to commit if all succeed or fail if anything fails. What you're describing maybe relates more to transaction isolation level, and it's actually possible to relax the isolation level so that you don't have the same ordering garuntees Or actually maybe not realted to isolation level, as we're talking about operations within the transaction, not how it responds to operations outside of the transaction

Angelelz•10mo ago

I understand that and I partially agree, my point is I don't think using promise.all would achieve any performance benefit over just running the promises as at the DB level it won't be parallel anyway?

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Transaction doesn't support Promise.all