B-tree index structure in DBMS Theory - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is a B-tree index structure in databases?

A B-tree index is a balanced tree data structure that helps databases find data quickly by keeping data sorted and allowing fast searches, insertions, and deletions.

beginner

Why is a B-tree index called 'balanced'?

Because all leaf nodes are at the same depth, ensuring that the time to find any data is similar, which keeps search times fast and predictable.

intermediate

How does a B-tree index improve database search performance?

It reduces the number of disk reads by organizing data in a tree where each node can have many children, so the database can skip large parts of data and find the target quickly.

intermediate

What happens when a node in a B-tree index becomes full?

The node splits into two nodes and the middle key moves up to the parent node, keeping the tree balanced and maintaining efficient search times.

beginner

Name two advantages of using a B-tree index in a database.

1. Fast data retrieval even with large datasets. 2. Maintains balance automatically to keep operations efficient.

What does the 'B' in B-tree stand for?

A Binary

B Balanced

C Block

D Basic

The 'B' in B-tree stands for 'Balanced' because the tree keeps all leaf nodes at the same depth.

In a B-tree, what happens when a node is full and a new key needs to be inserted?

A The node splits and the middle key moves up

B The node is deleted

C The tree becomes unbalanced

D The key is ignored

When a node is full, it splits into two nodes and the middle key moves up to keep the tree balanced.

Which of the following is a key benefit of using a B-tree index?

A Faster random data access

B Slower insertions

C Faster sequential scans

D No need for disk storage

B-tree indexes speed up random data access by reducing the number of disk reads.

How are keys stored in a B-tree node?

A In random order

B Only the largest key

C Sorted order

D Only the smallest key

Keys in a B-tree node are stored in sorted order to allow efficient searching.

What is the main reason B-trees are used in databases instead of binary trees?

A B-trees use less memory

B B-trees are easier to implement

C Binary trees are unbalanced by design

D B-trees handle large blocks of data efficiently

B-trees are designed to handle large blocks of data efficiently, reducing disk reads compared to binary trees.

Explain how a B-tree index keeps data balanced and why this is important for database performance.

Think about how the tree structure affects search time.

Describe the process that occurs when inserting a new key into a full node in a B-tree index.

Focus on how the tree adjusts to keep balance.