Oracle Indexes and Clusters Overview

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Questions and Answers

What is the purpose of indexes in Oracle databases?

  • Store data separately from the indexes
  • Automatically update indexes after new data is inserted (correct)
  • Use indexes only for queries and not for other SQL statements
  • Manually manage the indexes for each table

How does clustering help in boosting performance of join queries?

  • By storing related data in separate disk pages
  • By storing related data together on the same disk page (correct)
  • By creating multiple cluster indexes
  • By spreading data to different disk areas

What is a cluster column in Oracle databases?

  • A column that stores data separately from the cluster tables
  • A common column with the same data type and size in cluster tables (correct)
  • A column that is unique and indexed
  • A column that requires additional storage space

Which statement about cluster indexes is true?

<p>Cluster indexes require additional storage space (D)</p> Signup and view all the answers

How are indexes used by Oracle databases in SQL statements?

<p>Indexes are used for all SQL statements to find records (A)</p> Signup and view all the answers

What happens to index usage if columns referenced in the WHERE clause have indexes?

<p>Oracle automatically uses those indexes when appropriate (A)</p> Signup and view all the answers

What is the first step in creating clustered tables?

<p>Create a Cluster (C)</p> Signup and view all the answers

What is stored in an index segment in Oracle?

<p>Cluster Index (C)</p> Signup and view all the answers

What happens if a cluster index is dropped?

<p>Data in the cluster remains but cannot be accessed (A)</p> Signup and view all the answers

Can existing tables be moved into a cluster?

<p>No, tables have to be explicitly created under the cluster (A)</p> Signup and view all the answers

In a cluster index, how many entries are there per cluster key value?

<p>One entry per cluster key value (C)</p> Signup and view all the answers

What is required to access data in cluster tables?

<p>A Cluster Index (B)</p> Signup and view all the answers

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