You have altered a non-unique index to be invisible to determine if queries execute within an acceptable response time without using this index. Which two are possible if table updates are performed w

The correct answer is A. The index remains invisible. E. The index is updated by the DML on the table.. Unlike unusable indexes, an invisible index is maintained during DML statements. * Oracle 11g allows indexes to be marked as invisible. Invisible indexes are maintained like any other index, but they are ignored by the optimizer unless the OPTIMIZER_USE_INVISIBLE_INDEXES paramete

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Question

You have altered a non-unique index to be invisible to determine if queries execute within an acceptable response time without using this index. Which two are possible if table updates are performed which affect the invisible index columns?

Options

AThe index remains invisible.
BThe index is not updated by the DML statements on the indexed table.
CThe index automatically becomes visible in order to have it updated by DML on the table.
DThe index becomes unusable but the table is updated by the DML.
EThe index is updated by the DML on the table.

How the community answered

(29 responses)

A
93% (27)
C
3% (1)
D
3% (1)

Explanation

Unlike unusable indexes, an invisible index is maintained during DML statements. * Oracle 11g allows indexes to be marked as invisible. Invisible indexes are maintained like any other index, but they are ignored by the optimizer unless the OPTIMIZER_USE_INVISIBLE_INDEXES parameter is set to TRUE at the instance or session level. Indexes can be created as invisible by using the INVISIBLE keyword, and their visibility can be toggled using the ALTER INDEX command.

Topics

#Invisible indexes#DML operations#Index maintenance

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