Podcast
Questions and Answers
What is the main idea behind an ordered index?
What is the main idea behind an ordered index?
- To list important terms in a textbook in reverse alphabetical order along with page numbers
- To list important terms in a textbook based on their length
- To list important terms in a textbook in random order
- To list important terms in a textbook in alphabetical order along with page numbers (correct)
What is the purpose of a single-level index?
What is the purpose of a single-level index?
- To make it more efficient to search for a record in the data file (correct)
- To limit the access to only one level of the index
- To store multiple levels of indexes for complex searching operations
- To provide redundant information about the records
How is an index usually specified?
How is an index usually specified?
- In random order based on field value
- On multiple fields of the file
- In no specific order
- On one field of the file (correct)
What does an access path on the field represent?
What does an access path on the field represent?
How does an ordered index compare to a linear search?
How does an ordered index compare to a linear search?
Which of the following statements about indexes is true?
Which of the following statements about indexes is true?
What does a dense index have an entry for?
What does a dense index have an entry for?
What is a primary index defined on?
What is a primary index defined on?
What type of search is a better option when both the data file and the index file are ordered?
What type of search is a better option when both the data file and the index file are ordered?
What does a sparse (or nondense) index have entries for?
What does a sparse (or nondense) index have entries for?
Study Notes
Index Fundamentals
- An ordered index is a data structure that facilitates efficient retrieval of specific records from a file, based on the ordering of a specific field (key).
- A single-level index is used to speed up the retrieval of records from a file, by providing a quick way to locate specific records.
Index Specification
- An index is usually specified by the field(s) on which it is built, and the type of index (e.g., ordered, dense, sparse).
Access Path and Index
- An access path on the field represents a way to access the records of a file, using the index.
Index vs. Linear Search
- An ordered index is generally faster than a linear search, as it allows for direct access to specific records, rather than having to scan the entire file.
Index Characteristics
- A true statement about indexes is that they can be used to speed up retrieval of specific records from a file.
- A dense index has an entry for every key value in the index, allowing for direct access to every record in the file.
- A primary index is defined on the primary key of a file, and is used to provide a unique identifier for each record.
Search Options
- When both the data file and the index file are ordered, a binary search is a better option, as it can take advantage of the ordering to quickly locate specific records.
- A sparse (or nondense) index has entries for only some of the key values in the index, and is used when the index is very large or when the key values are widely scattered.
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Description
Test your knowledge of indexing structures for files with this quiz based on examples and concepts from Chapter 14 of the book 'Database Systems' by Ramez Elmasri and Shamkant B. Navathe.
