Quick recommendation: For the safest, standards-based choice, use
GUID / UUID v4 (fully random) or
GUID / UUID v7 (time-ordered for databases). Consider
Snowflake ID only when you operate at very large scale and have infrastructure for machine coordination.
Twitter Snowflake ID - github.com
Overview
Snowflake ID was created by Twitter to generate unique, time-ordered 64-bit integers across distributed systems. Unlike standard GUIDs / UUIDs (128 bits), Snowflake IDs are half the size and designed for systems that need machine-coordinated ID generation at massive scale.
When choosing an identifier for your application or database schema, you're usually deciding between standard GUIDs / UUIDs (governed by RFC 9562) and Snowflake ID, a non-standard but popular identifier format used in high-scale distributed systems.
Comparison table
| Property | GUID / UUID v4 | GUID / UUID v7 | Snowflake ID |
|---|
| Size | 128-bit | 128-bit | 64-bit |
|---|
| Encoding | Hex (8-4-4-4-12) | Hex (8-4-4-4-12) | Integer (19 digits) |
|---|
| Time-sortable | No | Yes (millisecond) | Yes (millisecond) |
|---|
| Standard | RFC 4122 and RFC 9562 | RFC 4122 and RFC 9562 | No RFC |
|---|
| Human-readable | Moderate
Hex with hyphens | Moderate
Hex with hyphens | Good
Simple integer |
|---|
| Database-friendly | Good
Native UUID support, but random | Excellent
Native support + sortable | Excellent
Compact BIGINT, sortable |
|---|
| Collision resistant | Excellent
122 bits random | Excellent
74 bits random | Good
12-bit sequence + coordination |
|---|
| Coordination required | No | No | Yes (machine IDs) |
|---|
| Best for | General-purpose IDs, privacy-friendly identifiers (no embedded data) and fully random | Database primary keys, event ordering, time-correlated IDs | High-scale distributed systems with machine coordination infrastructure |
|---|
Detailed comparison
Structure: 128 bits with 122 bits of randomness. No timestamp information.
- Pros: Universally supported, RFC standard, no time leakage, simple generation and no coordination needed
- Cons: Random insertion pattern can cause index fragmentation in some databases, larger storage than Snowflake ID
- Use when: You want maximum compatibility and don't need time-ordering
Example: 550e8400-e29b-41d4-a716-446655440000
Structure: 128 bits with 48-bit Unix millisecond timestamp prefix + 74 bits randomness.
- Pros: RFC standard, time-ordered, database-friendly, widely supported and no coordination needed
- Cons: Reveals creation timestamp (millisecond precision), larger storage than Snowflake ID
- Use when: You want time-ordering with RFC compliance for database primary keys
Example: 018f3f5e-1c2d-7a9b-8f10-3c4d5e6f7a8b
Snowflake ID (Twitter Snowflake)
Structure: 64-bit integer with 41-bit Unix millisecond timestamp + 10-bit machine ID + 12-bit sequence number.
- Pros: Compact storage (8 bytes vs 16 for UUID), time-ordered, efficient database indexing and designed for high-throughput systems
- Cons: Requires machine ID coordination, limited to 69 years from epoch (custom epoch needed), not RFC standard and clock dependency
- Use when: You need Twitter-scale ID generation with compact storage and have machine coordination infrastructure
Example: 1234567890123456789
Which one should you use?
- Choose GUID / UUID v4 if you want the safest default: widely supported, easy to store, no embedded metadata, simple generation and no coordination overhead.
- Choose GUID / UUID v7 if you want a standards-based ID that is time-ordered and typically behaves better as a database primary key than random GUIDs / UUIDs, without coordination overhead.
- Choose Snowflake ID if you operate at very large scale (Twitter scale), have infrastructure for machine ID coordination and clock synchronization, and need the storage efficiency of 64-bit integers.
Practical guidance for databases
If your main concern is database performance and index locality, you usually want identifiers that don't insert randomly across the index. That's the most common reason developers compare GUID / UUID v7 and Snowflake ID.
- Most compatible: GUID / UUID v4 (works everywhere, but can be random for indexes)
- Best "standard + sortable" combo: GUID / UUID v7 (time-ordered while staying a real GUID / UUID)
- Most compact but requires coordination: Snowflake ID (sortable 64-bit, but needs machine ID management)
Performance considerations
- B-tree indexes: Time-ordered IDs (v7, Snowflake) reduce page splits and improve insert performance in databases using B-tree indexes (PostgreSQL, MySQL, etc.).
- Storage overhead: Snowflake IDs are 64 bits (8 bytes) vs UUIDs at 128 bits (16 bytes) - half the storage. At scale, this can significantly reduce storage and memory requirements.
- Index size: Smaller IDs mean smaller indexes, which improves cache locality and query performance in high-volume systems.
- Throughput: Snowflake ID can generate up to 4096 IDs per millisecond per machine (12-bit sequence), sufficient for most high-throughput scenarios.
Interoperability and ecosystem support
GUID / UUID has the broadest support across programming languages, databases, and frameworks:
- Databases: Native GUID / UUID types in PostgreSQL, MySQL, SQL Server, Oracle, etc.
- Languages: Built-in support in Java, C#, Python, Go, Ruby, JavaScript, and many more
- APIs: JSON, REST, GraphQL commonly use GUID / UUID for resource identifiers
- ORMs: Entity Framework, Hibernate, Django ORM, and many others natively handle GUIDs / UUIDs
Snowflake ID requires custom implementation and infrastructure:
- Stored as
BIGINT in databases (no native Snowflake ID type) - Requires custom generators in each programming language
- Needs machine ID assignment and coordination infrastructure
- Requires clock synchronization (typically NTP) across machines
- Popular implementations available but not built into standard libraries
Other identifier formats
Beyond GUIDs / UUIDs and Snowflake ID, there are many other identifier formats each with their own trade-offs. For a comprehensive comparison of all popular identifier formats, see our complete identifier comparison guide.
For most applications requiring broad compatibility and standards compliance, standard GUIDs / UUIDs remain the recommended choice.
Warnings and trade-offs
- Identifiers are not secrets: GUID / UUID v4 / v7 and Snowflake ID are identifiers, not security tokens. Do not use them as access tokens or authentication secrets.
- Clock dependency: Snowflake ID requires accurate system clocks. Clock skew or backward clock adjustments can cause ID generation issues or duplicates. Proper NTP configuration is essential.
- Machine ID coordination: Snowflake ID requires assigning unique machine IDs (10 bits = 1024 machines max in standard implementation). This adds operational complexity.
- Limited timespan: With 41-bit timestamps, Snowflake IDs last 69 years from epoch. You must define a custom epoch (e.g., 2020-01-01) and plan for eventual exhaustion.
- Non-standard format: Snowflake ID is not an RFC UUID. Some APIs, ORMs, and databases assume GUID / UUID formatting and won't accept it without custom handling.
- Time leakage: time-ordered IDs can reveal approximate creation time. If that matters, prefer GUID / UUID v4 or treat IDs as private/internal.
- Interoperability matters: if you work across many systems or languages, GUIDs / UUIDs typically win due to universal support.
- Migration complexity: switching from one identifier format to another in an existing system can be challenging and may require data migration.
Frequently Asked Questions
No. Snowflake ID is a 64-bit integer identifier, not a 128-bit GUID / UUID. It's not governed by
RFC 9562. If you need a standards-based GUID / UUID, prefer
v4 or
v7.
Storage efficiency and performance. At Twitter scale (billions of IDs), 64-bit IDs reduce storage, memory, and network bandwidth by 50% compared to 128-bit UUIDs. A 64-bit integer also fits in a single CPU register, improving processing efficiency. The trade-off is reduced collision resistance and requiring machine coordination.
For most systems,
GUID / UUID v7 is the best choice because it provides time-ordering, RFC compliance, and no coordination overhead. Choose
Snowflake ID only if you're operating at massive scale where the 50% storage reduction matters and you can justify the coordination infrastructure. For simple universal IDs,
GUID / UUID v4 remains the easiest option.
No. Snowflake ID is 64 bits while GUID / UUID is 128 bits. You cannot losslessly convert between them. They have completely different structures and bit layouts. Choose one format for your system and stick with it for consistency. Migration requires generating new IDs and maintaining mapping tables if you need backward compatibility.
Common approaches include: Configuration files with static machine IDs, Service discovery systems (Consul, ZooKeeper) for dynamic assignment, Environment variables in containerized environments (Kubernetes), or Database-backed assignment where machines register and claim IDs. The key is ensuring no two machines share the same ID to prevent collisions.
Clock backward movement is dangerous for Snowflake IDs. Most implementations either wait until the clock catches up (blocking ID generation), refuse to generate IDs and throw an error, or use sequence overflow to continue generating IDs in the same millisecond. Proper NTP configuration and monotonic clock sources help prevent this issue.
Yes, as BIGINT. PostgreSQL doesn't have a native Snowflake ID type, but you can store them as
BIGINT. They'll be time-sortable by default since they're integer values. For native UUID support with broad compatibility, use
standard GUIDs / UUIDs with PostgreSQL's
uuid type.
Snowflake ID is similar to other coordinated ID systems like
KSUID (larger, Base62),
ULID (128-bit, Base32, no coordination), and
Sonyflake (Snowflake variant). Key differences: Snowflake is the most compact (64-bit) but requires coordination.
GUID / UUID v7 offers similar time-ordering without coordination overhead.
Choose
UUID v7 when you want time-ordering and database performance without coordination infrastructure.
RFC compliance, universal library support, and no machine ID management make UUID v7 easier to deploy. Choose Snowflake ID only when storage efficiency (64-bit vs 128-bit) matters enough to justify the coordination overhead.
Conclusion
For broad interoperability and standards compliance, choose a standard GUID / UUID: v4 for general-purpose fully random IDs or v7 for time-ordered database-friendly identifiers with millisecond precision.
Choose Snowflake ID when you operate at very large scale (Twitter scale), have infrastructure for machine ID coordination and clock synchronization, and need the storage efficiency of 64-bit integers. However, be aware that you'll need custom generation infrastructure and lose RFC compliance.