Sequential IDs

Generate sequential UUIDs for user registration and database storage.

Overview

When building applications that need unique identifiers for users, orders, or any entities, sequential UUIDs (v7) provide an excellent solution. They are time-ordered, globally unique, and work efficiently with database indexes.

Code

const std = @import("std");
const uuid = @import("uuid");

pub fn main() !void {
    var gpa: std.heap.DebugAllocator(.{}) = .init;
    defer _ = gpa.deinit();
    const allocator = gpa.allocator();

    var threaded: std.Io.Threaded = .init(allocator, .{});
    defer threaded.deinit();
    const io = threaded.io();

    const User = struct {
        id: uuid.UUID,
        name: []const u8,
        email: []const u8,
    };

    // Register users with v7 UUIDs
    const user_data = [_]struct { name: []const u8, email: []const u8 }{
        .{ .name = "Alice Johnson", .email = "alice@example.com" },
        .{ .name = "Bob Smith", .email = "bob@example.com" },
        .{ .name = "Charlie Brown", .email = "charlie@example.com" },
    };

    var users: [user_data.len]User = undefined;

    for (user_data, 0..) |data, idx| {
        // v7 UUIDs are time-ordered, ideal for sequential IDs
        const user_id = try uuid.UUID.v7Now(io);

        users[idx] = User{
            .id = user_id,
            .name = data.name,
            .email = data.email,
        };

        var id_buf: [36]u8 = undefined;
        std.debug.print("Registered: {s} -> {s}\n", .{
            data.name,
            user_id.encode(&id_buf),
        });
    }

    // Users are stored in chronological order
    for (users, 0..) |user, idx| {
        var id_buf: [36]u8 = undefined;
        std.debug.print("{d}. {s} - {s}\n", .{
            idx + 1,
            user.name,
            user.id.encode(&id_buf),
        });
    }
}

Run

zig build run-sequential-ids

Why v7 for Sequential IDs?

Benefit	Description
Time-ordered	UUIDs sort chronologically without extra columns
No central authority	Each node generates unique IDs independently
Database-friendly	B-tree indexes work efficiently with ordered keys
URL-safe	Standard UUID format works in APIs
Globally unique	No collisions across distributed systems

Database Schema

CREATE TABLE users (
  id UUID PRIMARY KEY,
  name VARCHAR(255) NOT NULL,
  email VARCHAR(255) UNIQUE NOT NULL
);

Batch Insert

BEGIN TRANSACTION;
INSERT INTO users (id, name, email) VALUES ('019ff869-6c60-7f33-...', 'Alice', 'alice@example.com');
INSERT INTO users (id, name, email) VALUES ('019ff869-6c60-7e4b-...', 'Bob', 'bob@example.com');
COMMIT;