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  1. Documentation
  2. DOCS-2225

Mention size limitation of reduce output document on map/reduce page

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    • Icon: Task Task
    • Resolution: Done
    • Icon: Major - P3 Major - P3
    • v1.3.11
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    Description

      http://docs.mongodb.org/manual/reference/method/db.collection.mapReduce/#requirements-for-the-reduce-function

      On the map/reduce page, some size limitations are mentioned (e.g. emit can only output 1/2 of BSON size), but it doesn't explicitly state that the reduce function is also bound by the 1/2 BSON size = 8MB limit.

      The error you get when trying to return a document larger than that limit is

      	"errmsg" : "exception: value too large to reduce",
      	"code" : 13070,

      This should be stated in the list of requirements for the reduce function.

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            andrew.aldridge@mongodb.com Andrew Aldridge
            thomas.rueckstiess@mongodb.com Thomas Rueckstiess
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              Created:
              Updated:
              Resolved:
              9 years, 21 weeks, 6 days ago