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  1. Core Server
  2. SERVER-41458

$natural hint overrides index filters

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Details

    • Bug
    • Status: Backlog
    • Major - P3
    • Resolution: Unresolved
    • None
    • None
    • Querying
    • ALL

    Description

      According to docs: https://docs.mongodb.com/manual/core/query-plans/#index-filters, Index Filters always override hints. However, according to the code path starting here $natural hint overrides index filters. 

      db.c.insert({a : 1})
      db.runCommand({planCacheSetFilter: "c", query: {}, indexes: [{ a : 1 }]});
      db.c.aggregate({$group: {_id: "$a"}})
      db.c.explain().aggregate({$group: {_id: "$a"}})
      db.c.explain().aggregate([{$group: {_id: "$a"}}], {hint: {$natural: 1}})
      

      Log Level 5 shows "Forcing a table scan due to hinted $natural".

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              backlog-query-optimization Backlog - Query Optimization
              misha.ivkov@mongodb.com Mikhail Ivkov (Inactive)
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                Updated: