Which three are true regarding the use of Storage Indexes?

Question

Options

• ADifferent storage regions may have different columns indexed for the same table.
• BA Storage index is automatically maintained by CELLSRV based on the filter columns of the offload SQL.
• CThe use of Storage indexes for a particular database can be disabled by using an I/O Resource Manager
• DStorage Indexes occupy space in the Smart Flash Cache.
• EThe use of Storage Indexes for particular categories of I/O can be disabled by using an I/O Resource
• FA maximum of eight table columns for any table are Indexed per storage region.

• A
  75% (24)
• C
  3% (1)
• D
  9% (3)
• E
  13% (4)

Explanation

• Storage indexes are used during smart scans. All the limitations to smart scans apply to storage indexes. They do not work with joins. Bind variables are supported, however it's slightly more restrictive than regular indexes/queries. * The storage index is stored in the memory on each of the Exadata storage cells and is created and maintained transparently. However, if a storage cell is shutdown or rebooted the storage index will be lost from memory and will be recreated on subsequent accesses to the data after the cell has been brought back online. * Storage Indexes are a very powerful capability provided in Exadata storage that helps avoid I/O operations. The Exadata Storage Server Software creates and maintains a Storage Index (that is, metadata about the database objects) in the Exadata cell. The Storage Index keeps track of minimum and maximum values of columns for tables stored on that cell. When a query specifies a WHERE clause, but before any I/O is done, the Exadata software examines the Storage Index to determine if rows with the specified column value exist in the cell by comparing the column value to the minimum and maximum values maintained in the Storage Index. If the column value is outside the minimum and maximum range, scan I/O for that query is avoided. Many SQL Operations run dramatically faster because large numbers of I/O operations are automatically replaced by a few lookups. To minimize operational overhead, Storage Indexes are created and maintained transparently and automatically by the Exadata Storage Server Software.

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