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added 56 characters in body

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edited Jan 25, 2022 at 7:51

3.1k
1
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16

One of the shortest one could be this one:

const counts = {}
db.collection.aggregate([
   { $project: { data: { $objectToArray: "$$ROOT" } } }
]).forEach(doc => {
   doc.data.forEach(val => {
      counts[val.k] =+= typeof counts[val.k] == "undefined" ? val.v ||: 0;counts[val.k] + val.v;
   })
})

I tried to find solution of $objectToArray, $group but most likely it will not work, because the size of document is limited to 16 MiBytes. Having "millions of documents" this limit will certainly exceeded.

One of the shortest one could be this one:

const counts = {}
db.collection.aggregate([
   { $project: { data: { $objectToArray: "$$ROOT" } } }
]).forEach(doc => {
   doc.data.forEach(val => {
      counts[val.k] =+ val.v || 0;
   })
})

One of the shortest one could be this one:

const counts = {}
db.collection.aggregate([
   { $project: { data: { $objectToArray: "$$ROOT" } } }
]).forEach(doc => {
   doc.data.forEach(val => {
      counts[val.k] = typeof counts[val.k] == "undefined" ? val.v : counts[val.k] + val.v;
   })
})

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created Jan 25, 2022 at 7:44

Wernfried Domscheit

3.1k
1
16
16

One of the shortest one could be this one:

const counts = {}
db.collection.aggregate([
   { $project: { data: { $objectToArray: "$$ROOT" } } }
]).forEach(doc => {
   doc.data.forEach(val => {
      counts[val.k] =+ val.v || 0;
   })
})