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  1. Core Server
  2. SERVER-49539

$bucketAuto does not account the memory used while running accumulator

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    • Type: Icon: Bug Bug
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 4.8.0
    • Affects Version/s: None
    • Component/s: None
    • Labels:
    • Fully Compatible
    • ALL
    • Hide 
      coll.drop();
for (let i = 0; i < 500; ++i) {
    for (let j = 0; j < 10; ++j) {
        assert.commandWorked(coll.insert({groupBy: i}));
    }
}

const res = coll.aggregate([
              {
                  $bucketAuto: {
                      groupBy: "$groupBy",
                      buckets: 500,
                     // This should create an array of 10MB size for each group, resulting in 5GB of memory usage overall.
                      output: {arr: {$push: "a".repeat(1000000)}} 
                  }
              },
              {$count: "c"}
          ])
          .toArray();
      Show
      coll.drop(); for (let i = 0; i < 500; ++i) { for (let j = 0; j < 10; ++j) { assert .commandWorked(coll.insert({groupBy: i})); } } const res = coll.aggregate([ { $bucketAuto: { groupBy: "$groupBy" , buckets: 500, // This should create an array of 10MB size for each group, resulting in 5GB of memory usage overall. output: {arr: {$push: "a" .repeat(1000000)}} } }, {$count: "c" } ]) .toArray();
    • Query 2020-08-24, Query 2020-09-07, Query 2020-09-21

      We account the memory used while running the sorter but not when running the accumulator. This could result in server consuming unlimited amount of memory while executing an aggregate command.

            Assignee:
            arun.banala@mongodb.com Arun Banala
            Reporter:
            arun.banala@mongodb.com Arun Banala
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              Created:
              Updated:
              Resolved: