UUID

Universally Unique Identifier

Medium — good to knowDatabase

ELI5 — The Vibe Check

A UUID is a randomly generated ID that looks like 'a3b4c5d6-...' and is practically guaranteed to be unique across the entire universe. Unlike auto-increment IDs (1, 2, 3), you can generate UUIDs on the client without asking the database first.

Real Talk

A UUID is a 128-bit identifier standardized by RFC 4122, typically represented as 32 hexadecimal characters in 8-4-4-4-12 format. Version 4 UUIDs are randomly generated with an extremely low collision probability. They are preferred over sequential integers when IDs must be globally unique or generated offline.

Show Me The Code

-- PostgreSQL with pgcrypto
CREATE TABLE sessions (
  id UUID DEFAULT gen_random_uuid() PRIMARY KEY,
  user_id UUID REFERENCES users(id)
);

When You'll Hear This

"Use UUIDs so users cannot guess sequential IDs." / "The frontend generates the UUID before sending the request."

Related Terms

Auto Increment

Auto increment means the database assigns the next ID number automatically every time you insert a row.

beginnerDatabase

Primary Key

A primary key is the unique ID that every row in a table must have. Like a social security number for your data — no two rows can have the same one.

beginnerDatabase

Table

A database table is exactly like a spreadsheet tab. It has columns across the top (name, email, age) and rows going down (one per person).

beginnerDatabase

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