Grouping MongoDB Data by Ignition Field Values: A Solution for Large Datasets - mongodb

Question

I want to group the data based on the values of the "ignition" field. If the "ignition" value is 1, all records with the value 1 should be grouped together until the next value of 0 is encountered, and so on.
I have 86400 records in MongoDB, and I want to query the data to achieve the desired output.
The data looks like this:
[
{
ignition: 1,
time: 112
},
{
ignition: 1,
time: 193
},
{
ignition: 0,
time: 115
},
{
ignition: 1,
time: 116
},
{
ignition: 1,
time: 117
},
{
ignition: 1,
time: 118
},
{
ignition: 0,
time: 119
},
{
ignition: 1,
time: 120
},
{
ignition: 1,
time: 121
},
{
ignition: 1,
time: 122
},
{
ignition: 0,
time: 123
},
]
I want the output like this:
{
time: [112,193],
time: [116,117,118],
time: [120,121,122]
}

Answer 1

db.collection.aggregate([
{
$setWindowFields: { //6. the output of this stage is, each set of adjacent documents having same $ignition will have a unique groupNum
partitionBy: null,
sortBy: {time: 1}, //4. from all documents sorted by $time
output: {
"groupNum": { //1. create a new field groupNum
$sum: { //2. by cumulatively adding
$cond: [
{$eq: ["$ignition",1]}, 0, 1 //3. modified $ignition field
]
},
window: {
documents: ["unbounded","current"] //5. starting from the beginning to current document
}
}
}
}
},
{
$match: {"ignition": 1} //7. retain $ignition : 1
},
{
$group: {
_id: "$groupNum", //8. group by groupNum
time: {$push: "$time"} //9. pushing the time to an array
}
},
{
$sort: {_id: 1} //10.sort as necessary
}
])
Demo