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Computing Statistics - Quiz

Each question is worth one point. Select the best answer or answers for each question.
 
1. When can you compute statistics on an index?
Please select all the correct answers.
  A. When you perform maintenance operations
  B. When you create the index
  C. At any time using DBMS_STATS or legacy ANALYZE command
  D. Only when the database is not operating

2. Which two conditions commonly lead to right-edge hot block contention or leaf block sparsity in a B-tree index?
Please select all the correct answers.
  A. The index uses a value that increases sequentially over time
  B. The index uses a character value for the index key
  C. The index is defined on multiple columns
  D. Earlier values in the underlying table are deleted over time, leaving sparse leaf blocks

3. What is a good reason to use a descending index?
Please select the best answer.
  A. The index is in danger of becoming unbalanced over time.
  B. Common queries require the data in the associated table to return rows with a value in descending order.
  C. It is easier to compute statistics on a descending index.
  D. You must have an equal number of ascending and descending indexes on a table.