Correctly handle maxTimeMS for db.runCommand explain

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    • Type: Improvement
    • Resolution: Unresolved
    • Priority: Major - P3
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    • Affects Version/s: None
    • Component/s: None
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    • Query Optimization
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      As noted by christopher.harris@mongodb.com (see comments for full slack thread context):

      The top-level maxTimeMS is respected:

      db.runCommand({
  explain: { ... }, 
  maxTimeMS: 1000
})

      Nested maxTimeMS in explain is not work:

      db.runCommand({ 
  explain: {
    ... ,
    maxTimeMS: 1000
  }
})

      Two possible solutions:
      1. Augment explain to accept it as an argument

      2. Validate the command on server-side and reject it if there are extra options to explain

      Repro:

      print("Top level maxTimeMS");
db.runCommand({
   explain: { find: "orders", filter: { $where: "sleep(1000) || true" } },
   maxTimeMS: 10
}); // Should error with "MongoServerError: operation exceeded time limit"

print("Explain nested maxTimeMS");
db.runCommand({
   explain: { find: "orders", filter: { $where: "sleep(1000) || true" }, maxTimeMS: 10},
}); // Runs to completion

            Assignee:
            Unassigned
            Reporter:
            Naafiyan Ahmed
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              Created:
              Updated: