Podcast
Questions and Answers
What is the main idea behind an ordered index?
What is the main idea behind an ordered index?
What is the purpose of a single-level index?
What is the purpose of a single-level index?
How is an index usually specified?
How is an index usually specified?
What does an access path on the field represent?
What does an access path on the field represent?
Signup and view all the answers
How does an ordered index compare to a linear search?
How does an ordered index compare to a linear search?
Signup and view all the answers
Which of the following statements about indexes is true?
Which of the following statements about indexes is true?
Signup and view all the answers
What does a dense index have an entry for?
What does a dense index have an entry for?
Signup and view all the answers
What is a primary index defined on?
What is a primary index defined on?
Signup and view all the answers
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?
Signup and view all the answers
What does a sparse (or nondense) index have entries for?
What does a sparse (or nondense) index have entries for?
Signup and view all the answers
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.
Studying That Suits You
Use AI to generate personalized quizzes and flashcards to suit your learning preferences.
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.
