6.5830 Lecture 1 (WIP)

What is a database

collection of structured data
organized as records + relationships between them

Why should we care?

Real world impact

Concepts

Data modeling & layout

Systematic approach to structuring / representing data
Constistency, sharing, efficiency of access to persistent data

Declarative Querying and Query Processing

Ask for data
Compiler finds optimal plan
Low-level techniques

Consistency / Transactions + Concurrency Control

Basically, ACID:

Atomicity: Operations are all-or-nothing
Consistency: Semantics are well-defined, invariants are respected
Isolation: Concurrent transactions are isolated from each other
Durability: 🤞 Hope our data doesn’t get lost

Example - Zoo

A zoo website might have:

admin interface that allows adding and editing animals
public interface for viewing pictures and maps
zookeeper interface for finding hungry animals

Operations

move all snakes to new building
- need to change many files
multiple admins editing page at the same time
- need concurrency control
system may crash mid-update
- need all-or-nothing operations
need to find animal that was fed the longest ago
- need efficient plan from database

Databases address all these issues and more

Date: August 27, 2024

Tags: lecture