CODEWITHSUNDEEP
javascriptnode.jsmongodbmongojs
RainingChain
RainingChain

Reputation: 7772

MongoDb: Is forEach good memory wise?

I have a lot of data to fetch from a mongodb database. I can't load all the data at once on the server because it's too big and I would run out of memory.

If I use forEach, will it fetch everything and load everything on the server then apply the function on each of them?

OR

Will it fetch the first element, apply function, load second element, apply function... until the last one?

Upvotes: 1

Views: 539

Answers (1)

Neil Lunn
Neil Lunn

Reputation: 151122

No it does not load everything. Here is basically why:

> db.hotel.find().forEach
function ( func ){
    while ( this.hasNext() )
        func( this.next() );
}

So you see that "under the hood" all this is doing is providing a "convenience" wrapper over the standard cursor iterator methods.

It's just a helper, whether in the shell or in general driver functions.

But if your "driver" allows, then use a "streaming" interface instead, which is a much better approach.

Upvotes: 3

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