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  1. Core Server
  2. SERVER-47001

Reduce number of small buffer allocations for index builds

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    • Type: Icon: Improvement Improvement
    • Resolution: Fixed
    • Priority: Icon: Major - P3 Major - P3
    • 4.7.0
    • Affects Version/s: None
    • Component/s: None
    • None
    • Fully Compatible
    • Execution Team 2020-04-06, Execution Team 2020-04-20
    • 0

      Index builds allocate a single, small buffer for each key generated. For index builds with small keys, much of the index build CPU time is spent just in memory allocation.

      It is generally faster to allocate fewer, larger memory regions than numerous, smaller ones. We can speed up index builds by allocating a few large buffers for key generation and sorting the pointers to keys within those buffers.

      This has the added benefit of having better cache locality for sorting since all keys will be nearby in memory.

            Assignee:
            henrik.edin@mongodb.com Henrik Edin
            Reporter:
            louis.williams@mongodb.com Louis Williams
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              Created:
              Updated:
              Resolved: