meteorisgreat:ferretdb-index-fix

This packages provides compatibility for Meteor.js and FerretDB when used together with accounts-password.

What it does

Sequential index creation – Wraps Mongo.Collection.prototype.createIndexAsync in a promise queue so every index is built one at a time. This avoids the deadlock detected error that FerretDB/PostgreSQL can raise when multiple concurrent CREATE INDEX statements are issued by Meteor packages (e.g. accounts-base and accounts-password).

Once FerretDB/PostgreSQL gain robust concurrent‑index support, this package will no longer be useful.

Installation

meteor add meteorisgreat:ferretdb-index-fix

Ensure it appears before the accounts packages in .meteor/packages so the wrapper is in place first.

Background

Why does FerretDB deadlock when used with Meteor.js together with accounts-password?

Meteor’s accounts packages run in parallel

Package	Indexes it tries to create (all sparse + unique unless noted)
accounts-base	username, emails.address, services.resume.loginTokens.hashedToken, services.resume.loginTokens.token,services.resume.haveLoginTokensToDelete (sparse only), services.resume.loginTokens.when (sparse only),services.password.reset.when (sparse only), services.password.enroll.when (sparse only)
accounts-password	services.email.verificationTokens.token, services.password.reset.token, services.password.enroll.token

When Meteor starts up, the sequential createIndexAsync calls in https://github.com/meteor/meteor/blob/devel/packages/accounts-base/accounts_server.js and https://github.com/meteor/meteor/blob/devel/packages/accounts-password/password_server.js run in parallel, which leads to concurrent CREATE INDEX in PostgreSQL, which leads to a deadlock error.

Note: the accounts packages each actually call createIndexAsync sequentially, but because the two packages run at the same time, we still end up with concurrent createIndexAsync calls. Also: just using accounts-base will work, but using accounts-password, which relies on accounts-base, will lead to this concurrent index creation on the same table.

This leads to the error MongoServerError: deadlock detected. Meteor re-throws that error as
[An error occurred when creating an index for collection "users"],
and startup aborts.

How this package fixes it

meteorisgreat:ferretdb-index-fix patches Mongo.Collection.prototype.createIndexAsync so the calls form a promise queue.

Index definitions are not altered; they are simply run sequentially, which Postgres can handle without deadlocking.