# Quiz

+ 1) Which of the following factors can cause TiDB Server abnormal memory usage? (Please select 3)
  + A. Large transaction cause memory enlargement
  + B. A large amount of non-essential data SQL return to TiDB due to misalignment of the execution plan
  + C. GO 's memory reclamation mechanism may also lead to abnormal memory usage
  + D. ADD Index operation, write reorg also takes up a lot of memory during the stage

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Answers: a, b, c