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  1. Core Server
  2. SERVER-88445

Investigate whether ProjectStageCovered can reuse BSON buffer from index scan

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    • Type: Icon: Task Task
    • Resolution: Won't Fix
    • Priority: Icon: Major - P3 Major - P3
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    • Query Optimization
    • QO 2024-04-15, QO 2024-04-29

      ProjectionStageCovered::transform will always allocate a new BSONObj to put fields in. Investigate whether we can re-use the BSON buffer from the index scan and shuffle around the bytes to avoid this allocation (in SERVER-87103, this accounts for ~50% of allocations in the workload). Since the projection is covering, we know that the BSON not get larger.

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            Assignee:
            ben.shteinfeld@mongodb.com Ben Shteinfeld
            Reporter:
            ben.shteinfeld@mongodb.com Ben Shteinfeld
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