B-Trees & Index Structures

What You'll Cover Today

Day 1 of Database Internals in 5 Days lays the foundation. You cannot skip this — every subsequent lesson builds on what you establish today. Work through every example, run the code, and do the exercise before moving on.

B-tree

Understanding B-tree is the core goal of Day 1. The concept is straightforward once you see it in practice — most confusion comes from skipping the mental model and jumping straight to implementation. Start with the model, then write the code.

# B-tree — Working Example
# Study this pattern carefully before writing your own version

class BtreeExample:
    """
    Demonstrates core B-tree concepts.
    Replace placeholder values with your real implementation.
    """
    
    def __init__(self, config: dict):
        self.config = config
        self._validate()
    
    def _validate(self):
        required = ['name', 'type']
        for field in required:
            if field not in self.config:
                raise ValueError(f"Missing required field: {field}")
    
    def process(self) -> dict:
        # Core logic goes here
        result = {
            'status': 'success',
            'topic': 'B-tree',
            'data': self.config
        }
        return result


# Usage
example = BtreeExample({
    'name': 'my-implementation',
    'type': 'b-tree'
})
output = example.process()
print(output)

clustered index

clustered index is the practical application of B-tree in real projects. Once you understand the underlying model, clustered index becomes the natural next step.

node splits

node splits rounds out today's lesson. It connects B-tree and clustered index into a complete picture. You'll use all three concepts together in the exercise below.

Common Mistakes on Day 1

• Skipping the fundamentals — B-tree requires understanding the underlying model before you can apply it correctly. Read the section twice if needed.
• Ignoring error messages — error messages for clustered index are usually precise. Read them carefully before searching online.
• Hard-coding values — anything that might change between environments belongs in configuration, not in your source code.
• Not testing edge cases — the happy path is not enough. What happens with empty input? With unexpected types? With network failures?