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

Recall & Review

beginner

What is a B+ tree in database indexing?

A B+ tree is a balanced tree data structure used in databases to store indexes. It keeps data sorted and allows fast search, insert, and delete operations by maintaining all values in leaf nodes linked sequentially.

intermediate

How does a B+ tree differ from a B-tree?

In a B+ tree, all actual data records are stored only at the leaf nodes, which are linked in a sequence. Internal nodes only store keys to guide searches. In contrast, a B-tree stores data in both internal and leaf nodes.

beginner

Why are leaf nodes in a B+ tree linked together?

Leaf nodes in a B+ tree are linked to allow efficient range queries and ordered traversal. This means you can quickly scan through a range of values without going back up the tree.

intermediate

What happens when a node in a B+ tree becomes full?

When a node is full, it splits into two nodes, and the middle key moves up to the parent node. This keeps the tree balanced and ensures that operations remain efficient.

beginner

What is the main advantage of using a B+ tree for database indexes?

The main advantage is that B+ trees provide fast and efficient access to data with logarithmic search time, support for range queries, and a balanced structure that keeps operations quick even as data grows.

Where are the actual data records stored in a B+ tree?

A Only in leaf nodes

B Only in internal nodes

C In both internal and leaf nodes

D Nowhere, B+ tree stores only keys

In a B+ tree, all actual data records are stored only in the leaf nodes.

Why are leaf nodes linked in a B+ tree?

A To store parent pointers

B To store duplicate keys

C To reduce tree height

D To speed up range queries and ordered traversal

Leaf nodes are linked to allow efficient scanning of data in order, which helps with range queries.

What triggers a node split in a B+ tree?

A When a node has too few keys

B When leaf nodes are unlinked

C When a node becomes full

D When the root node is empty

A node splits when it becomes full to maintain balance and efficiency.

Which of the following is NOT true about B+ trees?

A Data is stored only in internal nodes

B They allow fast search operations

C They keep data sorted

D Leaf nodes are linked sequentially

Data is stored only in leaf nodes, not internal nodes.

What is the main benefit of B+ trees in databases?

A They use less memory than hash indexes

B They provide fast, balanced access and support range queries

C They store data in random order

D They do not require balancing

B+ trees keep data balanced and sorted, enabling fast searches and efficient range queries.

Explain the structure of a B+ tree and how it supports efficient database indexing.

Think about how the tree keeps data sorted and balanced.

Describe what happens during a node split in a B+ tree and why it is important.

Consider how the tree grows and stays balanced.