在Meteor中删除Mongo数据库集合

Question

Is there any way to drop a Mongo Database Collection from within the server side JavaScript code with Meteor? (really drop the whole thing, not just Meteor.Collection.remove({}); it's contents)

In addition, is there also a way to drop a Meteor.Collection from within the server side JavaScript code without dropping the corresponding database collection?

Why do that?

• Searching in the subdocuments (subdocuments of the user-document, eg userdoc.mailbox[12345] ) with underscore or similar turns out quiet slow (eg for large mailboxes).
• On the other hand, putting all messages (in context of the mailbox-example) of all users in one big DB and then searching* all messages for one or more particular messages turns out to be very, very slow (for many users with large mailboxes), too.
• There is also the size limit for Mongo documents, so if I store all messages of a user in his/her user-document, the mailbox's maximum size is < 16 MB together with all other user-data.

So I want to have a database for each of my user to use it as a mailbox, then the maximum size for one message is 16 MB (very acceptable) and I can search a mailbox using mongo queries.

Furthemore, since I'm using Meteor, it would be nice to then have this mongo db collection be loaded as Meteor.Collection whenever a user logs in. When a user deactivates his/her account, the db should of course be dropped, if the user just logs out, only the Meteor.Collection should be dropped (and restored when he/she logs in again).

To some extent, I got this working already, each user has a own db for the mailbox, but if anybody cancels his/her account, I have to delete this particular Mongo Collection manually. Also, I have do keep all mongo db collections alive as Meteor.Collections at all times because I cannot drop them.

This is a well working server-side code snippet for one-collection-per-user mailboxes:

var mailboxes = {};

Meteor.users.find({}, {fields: {_id: 1}}).forEach(function(user) {
    mailboxes[user._id] = new Meteor.Collection("Mailbox_" + user._id);
});

Meteor.publish("myMailbox", function(_query,_options) {
    if (this.userId) {
        return mailboxes[this.userId].find(_query, _options);
    };
});

while a client just subscribes with a certain query with this piece of client-code:

myMailbox = new Meteor.Collection("Mailbox_"+Meteor.userId());
Deps.autorun(function(){
    var filter=Session.get("mailboxFilter");
    if(_.isObject(filter) && filter.query && filter.options)
        Meteor.subscribe("myMailbox",filter.query,filter.options);
});

So if a client manipulates the session variable "mailboxFilter", the subscription is updated and the user gets a new bunch of messages in the minimongo.

It works very nice, the only thing missing is db collection dropping.

Thanks for any hint already!

*I previeously wrote "dropping" here, which was a total mistake. I meant searching.

Answer 1

A solution that doesn't use a private method is:

myMailbox.rawCollection().drop();

This is better in my opinion because Meteor could randomly drop or rename the private method without any warning.

Answer 2

You can completely drop the collection myMailbox with myMailbox._dropCollection() , directly from meteor.

I know the question is old, but it was the first hit when I searched for how to do this

Answer 3

Searching in the subdocuments...

Why use subdocuments? A document per user I suppose?

each message must be it's own document

That's a better way, a collection of messages, each is id'ed to the user. That way, you can filter what a user sees when doing publish subscribe.

dropping all messages in one db turns out to be very slow for many users with large mailboxes

That's because most NoSQL DBs (if not all) are geared towards read-intensive operations and not much with write-intensive. So writing (updating, inserting, removing, wiping ) will take more time.

Also, some online services (I think it was Twitter or Yahoo) will tell you when deactivating the account: "Your data will be deleted within the next N days." or something that resembles that. One reason is that your data takes time to delete.

The user is leaving anyway, so you can just tell the user that your account has been deactivated, and your data will be deleted from our databases in the following days. To add to that, so you can respond to the user immediately, do the remove operation asynchronously by sending it a blank callback.