Mongo aggregate fails?

From: Damon Casale <damoncasale@xxxxxxxxx>
To: mongodb-user <mongodb-user@xxxxxxxxxxxxxxxx>
Date: Sun, 17 Apr 2016 15:32:36 -0700 (PDT)
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I'm unable to run a Mongo aggregate command.  It prints "..." in the 
command shell and never finishes.  Even explain stalls.

I'm trying to do this:

db.listings.aggregate([{$group: {'_id': {AssignedNeighborhood: 
$AssignedNeighborhood}, 'count': {$sum: 1}}], {explain: true})

What am I doing wrong?  Please help.

Mongo version is 2.6.11.  And yes, I have an index on AssignedNeighborhood.

Damon

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Why ads?