You are monitoring and evaluating a create index statement on your Database Machine and have run the following query after executing statement, providing the output. Shown: Select two reasons why…

Question

Exhibit

Options

• AThere are huge numbers of migrated rows in the table on which the index is being built.
• BThere is an uncommitted transaction that has modified one block of the table on which the index is being
• CThere is a transaction that has modified one block of the table on which the index is being built in each cell,
• DThere are huge numbers of chained rows in the table on which the index is being built.
• EThere is a ROWID column in the table on which the index is being built.

• A
  79% (15)
• B
  11% (2)
• C
  5% (1)
• E
  5% (1)

Explanation

A: It could be that row migration. D: It could be that row migration or chained rows could cause it. * Some facts about scans: Scans exists in "OLTP" systems Exadata smart scan requires a direct path read. A direct path read is chosen at runtime based on internal heuristics The STORAGE clause in an explain plan doesnt necessarily mean you will perform a smart scan. * The buffer caching in certain "OLTP" environments can occasionally induce conventional reads when smart scan is faster. * Typically see cell multiblock physical read instead of cell smart table scan waits * No one-size-fits-all solution can be given here but it is very fixable.

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