CODEWITHSUNDEEP
node.jsfirebase
Baz
Baz

Reputation: 2297

Implications of nested transactions in Firebase?

I am running a transaction to update an item that needs to be stored in two keys. To accomplish this, I have setup a nested transaction as follows, and it seems to run as expected:

firebaseOOO.child('relationships/main').child(accountID).child(friendAccountID).transaction(function(data) {
    data.prop = 'newval';
    firebaseOOO.child('relationships/main').child(friendAccountID).child(accountID).transaction(function(data) {
        return r;
    });
    return r;
});

Are there any gotchas or possible unexpected implications to this? I am most worried about getting stuck in some sort of transaction loop under load, where each transaction cancels the other out forcing them both to restart, or similar.

Is there a better way of doing this?

I am using the NodeJS client.

Upvotes: 3

Views: 1911

Answers (1)

Greg Soltis
Greg Soltis

Reputation: 1434

You probably don't want to start another transaction from within the callback to the first one. There is no guarantee as to how many times the function for your first transaction will run, particularly if there is a lot of contention at the location you are trying to update.

A better solution, which I believe you hit on in your other question, is to start the second transaction from the completion callback, after checking that the first one committed.

Upvotes: 4

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