Which two statements are true about the B-tree Index?

Question

Options

• AThe leaf blocks in the index are doubly linked.
• BThe leaf node stores a bitmap for each key value.
• CRows with a NULL value in key columns also have entries in the Index.
• DThe deletion of a row from the table causes a logical deletion in the index leaf block and the space

• A
  78% (31)
• B
  10% (4)
• C
  13% (5)

Explanation

https://docs.oracle.com/database/121/CNCPT/indexiot.htm#CNCPT88836 The leaf blocks contain every indexed data value and a corresponding rowid used to locate the actual row. Each entry is sorted by (key, rowid). Within a leaf block, a key and rowid is linked to its left and right sibling entries. The leaf blocks themselves are also doubly linked How the Database Maintains Indexes The database automatically maintains and uses indexes after they are created. The database also automatically reflects changes to data, such as adding, updating, and deleting rows, in all relevant indexes with no additional actions required by users. Retrieval performance of indexed data remains almost constant, even as rows are inserted. However, the presence of many indexes on a table degrades DML performance because the database must also update the

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