MongoDB is complaining because you have an unrecognised pipeline stage specification "count": { "$sum": 1 }
in your pipeline.
Your original pipeline when formatted properly
db.hashtag.aggregate([
{
"$group": {
"_id": {
"year": { "$year": "$tweettime" },
"dayOfYear": { "$dayOfYear": "$tweettime" },
"interval": {
"$subtract": [
{ "$minute": "$tweettime" },
{ "$mod": [{ "$minute": "$tweettime"}, 15] }
]
}
}
},
"count": { "$sum": 1 } /* unrecognised pipeline specification here */
}
])
should have the aggregate accumulator $sum
within the $group
pipeline as:
{
"$group": {
"_id": {
"year": { "$year": "$tweettime" },
"dayOfYear": { "$dayOfYear": "$tweettime" },
"interval": {
"$subtract": [
{ "$minute": "$tweettime" },
{ "$mod": [{ "$minute": "$tweettime"}, 15] }
]
}
},
"count": { "$sum": 1 }
}
}
])