mongoose.syncIndexes() and Connection#syncIndexes(): run syncIndexes() on all registered models

[AbdelrahmanHafez]

So, in mongoose 5.2.0 we introduced Model.syncIndexes(), and I've found that feature quite useful, I'd like to make it easier for people to utilize it.

Following are a few ideas on how we can do that:

• Create a new option: mongoose.set('syncIndexes', true);, which would automatically attempt to syncIndexes on connecting to the database. I assume that most people would expect that changing an index in the schema would reflect on the database, so I'd argue that this option should be set to true by default on mongoose v7.
• Create a new convenience static mongoose.syncIndexes(); which would internally loop over all the models and sync their indexes. The reasoning behind doing that is because I run multiple instances of node, and would like to use mongoose.syncIndexes(); only on one of the node instances in order to avoid multiple instances trying to sync at once, avoiding possible race conditions.

What do you think?
@vkarpov15 @IslandRhythms @ahmedelshenawy25

[IslandRhythms]

Both have their benefits, I think option 2 gives more control to the user when to invoke it as opposed to option 1 where it will always be invoked.

[AbdelrahmanHafez]

@IslandRhythms
I've been thinking of introducing both options. I agree that mongoose.syncIndexes(); gives more control and I would probably use it over mongoose.set('syncIndexes', true); in my apps.

[vkarpov15]

I like both options. I think adding mongoose.syncIndexes() in v6.1 would be a nice new feature to add.