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  1. Core Server
  2. SERVER-4566

In new aggregation framework, $sort, $limit in the pipeline seems loading all the matched data into memory. When we tried to improve the performance by leveraging multi thread aggregation, this makes it much slower than single thread

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    Details

    • Type: Bug
    • Status: Closed
    • Priority: Major - P3
    • Resolution: Fixed
    • Affects Version/s: 2.1.1
    • Fix Version/s: None
    • Component/s: Aggregation Framework
    • Labels:
      None
    • Environment:
      OSX 10.6, Java, mongodb is built from Dec. 15 master branch.
    • Operating System:
      OS X

      Description

      Overall new aggregation framework is faster than map-reduce in our application. But when I tried to further improve the performance by sending multiple aggregation commands in multiple threads, then get the final aggregation done in app space, I noticed each thread will load lot of data to memory which makes each command take minutes to finish. (I do have index on sort key)

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                  Updated:
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