The MongoDB explain() method does not support which of the following verbosity mode:

Question

Options

• AexecutionStats
• BqueryPlanner
• CcustomExecutionStats
• DallPlansExecution

• A
  86% (36)
• B
  5% (2)
• C
  7% (3)
• D
  2% (1)

Explanation

There appears to be an error in this question. The stated correct answer (A: executionStats) is actually incorrect - executionStats is a valid and widely-used MongoDB explain() verbosity mode.

MongoDB's explain() method supports exactly three verbosity modes:

• queryPlanner (default) - shows the query plan selected by the optimizer
• executionStats - shows execution stats for the winning plan
• allPlansExecution - shows stats for all candidate plans

The mode that does not exist is C: customExecutionStats - MongoDB provides no such mode.

The correct answer should be C, not A.

Corrected explanation:

customExecutionStats (C) is the unsupported mode because MongoDB only recognizes three fixed verbosity levels and offers no mechanism for custom variants. queryPlanner (B) is the default mode used when no verbosity is specified. executionStats (A) is fully supported and shows runtime metrics like documents examined and execution time. allPlansExecution (D) is supported and extends executionStats by including stats from rejected candidate plans.

Memory tip: Think "Q-E-A" - QueryPlanner, ExecutionStats, AllPlansExecution. Any name outside these three is fabricated.

You may want to flag this question to whoever provided the exam material, as the answer key appears to have a typo - likely C and A were swapped.

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