What This Video Covers
PostgreSQL UUID tutorial videos cover everything from basic setup to advanced index performance — the native uuid type, built-in generator functions, the PostgreSQL 18 uuidv7() addition, and how to benchmark the difference.
Skill level: Beginner to advanced (varies by video) Best for: Backend developers and DBAs using PostgreSQL as their primary database
Key Concepts You Will Learn
1. The PostgreSQL uuid column type
PostgreSQL has a first-class uuid type that stores 16 bytes internally — not a string:
CREATE TABLE orders (
id uuid PRIMARY KEY,
status text NOT NULL
);
The type accepts standard hyphenated strings on input and outputs them on SELECT. No VARCHAR(36) needed — the native type is more efficient and the query planner understands it.
2. Generator functions by PostgreSQL version
| Version | UUID v4 | UUID v7 |
|---|---|---|
| 14–17 | gen_random_uuid() | uuid_generate_v7() via pg_uuidv7 extension |
| 18+ | gen_random_uuid() | uuidv7() built-in |
-- PostgreSQL 18
CREATE TABLE orders (
id uuid PRIMARY KEY DEFAULT uuidv7(),
status text NOT NULL
);
INSERT INTO orders (status) VALUES ('pending'); -- id generated server-side
3. Index performance benchmark
Videos often show EXPLAIN ANALYZE or pgbench results comparing:
- Integer BIGSERIAL: baseline, always appends to rightmost leaf
- UUID v4: random inserts, page splits, fragmented index
- UUID v7: near-BIGSERIAL performance, timestamp-clustered inserts
The fragmentation from UUID v4 becomes measurable above ~500k rows and severe above ~5M rows on default PostgreSQL settings.
4. Extension approach for PG 14–17
-- Install pg_uuidv7 extension
CREATE EXTENSION IF NOT EXISTS pg_uuidv7;
-- Use same API as PG 18 built-in
SELECT uuid_generate_v7(); -- identical semantics to uuidv7()
The pg_uuidv7 extension provides uuid_generate_v7() with identical output to the PG 18 built-in — bridging the gap for teams that cannot yet upgrade.
5. Querying by UUID v7 time range
Because UUID v7 values sort chronologically, you can query by time range using a UUID comparison:
-- All orders created in the last hour
SELECT * FROM orders
WHERE id > (
SELECT uuidv7_sub_interval(uuidv7(), '1 hour'::interval)
)
ORDER BY id;
This uses the primary key index — no separate created_at index needed for approximate time-range queries.
Related Reading
- PostgreSQL 18 Ships Native UUID v7
- UUID in Databases — full storage guide
- Zero-Downtime Migration from UUID v4 to v7
- UUID vs Auto-Increment Primary Keys
- UUID Byte Layout — timestamp field position
- Lexicographical Order — why v7 sorts by time
Watch on YouTube
Search for PostgreSQL UUID tutorial videos on YouTube ↗
Generate and Test
- Generate a UUID v7 — paste directly into PostgreSQL
- UUID Decoder — verify the timestamp embedded in the UUID
Frequently asked questions
Do videos on UUID database performance actually explain B-tree fragmentation?
Good UUID database performance videos explain that UUID v4 causes B-tree page splits because each new value inserts at a random position, fragmenting the index. UUID v7 solves this — its timestamp prefix means consecutive inserts cluster at the rightmost leaf, the same behaviour as auto-increment. See UUID Database Primary Keys video walkthrough and the full UUID in Databases guide.
Does PostgreSQL 18 support UUID v7 natively?
Yes. PostgreSQL 18 ships a built-in uuidv7() function that generates RFC 9562-compliant UUID v7 values directly in SQL — no extensions or application-level generation required. The values store in the existing uuid column type unchanged.
Do UUIDs hurt database index performance?
UUID v4 does — its randomness causes every insert to land at a different leaf page, leading to page splits and poor cache locality. UUID v7 embeds a millisecond timestamp so consecutive inserts cluster together, behaving like an auto-increment integer for B-tree purposes.
What is the best way to generate UUIDs in PostgreSQL?
In PostgreSQL 18+, use the built-in uuidv7() function as a column default — it generates time-sortable UUID v7 values server-side, so every insert path (ORM, raw SQL, migration) gets a v7 automatically. In PostgreSQL 14–17, use gen_random_uuid() for UUID v4, or the pg_uuidv7 extension for UUID v7 with the same semantics as the PG 18 built-in. See PostgreSQL 18 Ships Native UUID v7.
How do I migrate a PostgreSQL table from UUID v4 to v7?
Existing rows do not need to change — the uuid column type stores both v4 and v7 as identical 128-bit values. The migration is only about new inserts: in PostgreSQL 18, run ALTER TABLE orders ALTER COLUMN id SET DEFAULT uuidv7();. For earlier versions, update application code to generate v7. See Zero-Downtime Migration from UUID v4 to v7.