xid vs UUID: which is better for web APIs?

xid is better if you need smaller, sortable IDs for logging or database keys, as it's 20 chars vs UUID's 36 and embeds time. However, UUIDs are more standardized and cryptographically secure in versions like v4, so choose UUID for security or interoperability needs.

How to generate xid in Go with a custom machine ID?

Set the XID_MACHINE_ID environment variable to a 3-byte value before running your Go application, as mentioned in the notes. This allows fine-tuning for specific deployments, though the default uses host and process identifiers.

Is xid sortable and how does it compare to Snowflake?

Yes, xid is K-ordered and sortable due to embedded time, similar to Snowflake. But unlike Snowflake, it doesn't require configuration or central servers, making it simpler, though Snowflake offers 64-bit IDs and may handle higher throughput with setup.

What happens if the system clock changes or skews with xid?

xid depends on system time, so clock skew could cause non-chronological IDs or duplicates. It's not designed for environments with unreliable clocks; consider alternatives with timestamp corrections or centralized coordination in such cases.

Can I use xid as a primary key in databases like PostgreSQL?

Yes, its 12-byte binary format is compatible with BLOB or bytea types, and sortability aids indexing. However, ensure your database supports the size and encoding; PostgreSQL ports exist, but native UUID might be more integrated.

How many xids can I generate per second without collisions?

Up to 16,777,216 per host/process per second, due to the 3-byte counter. For most applications, this is sufficient, but monitor usage in high-frequency scenarios like real-time analytics to avoid limits.

xid — Globally Unique ID Generator

What is xid?

xid is a globally unique ID generator library for Go, based on the Mongo Object ID algorithm. It produces compact, sortable 12-byte identifiers with a 20-character base32hex string representation, designed for web and server applications without requiring configuration or central coordination.

Target Audience

Go developers building distributed systems, web services, or databases who need efficient, sortable unique identifiers without setup overhead.

Value Proposition

Developers choose xid for its balance of small size, built-in sortability, and zero-configuration design, offering better performance and simplicity compared to UUIDs or Snowflake-like systems.

xid is a globally unique id generator thought for the web

Use Cases

Best For

Generating sortable primary keys in distributed databases
Adding request IDs to web server logs for tracing
Creating compact, URL-safe identifiers for API resources
Replacing UUIDs in Go applications where smaller, sortable IDs are beneficial
Embedding timestamps in IDs for chronological ordering without extra fields
Building stateless services that need unique IDs without central coordination

Not Ideal For

Applications requiring cryptographically secure, unpredictable IDs (e.g., security tokens or anti-fraud systems)
Systems needing sub-millisecond timestamp precision in IDs for fine-grained event ordering
High-throughput scenarios where a single host/process must generate over 16 million unique IDs per second

Pros & Cons

Pros

Compact and Efficient

At 12 bytes binary and 20 characters string, it's smaller than UUIDs (16 bytes, 36 chars), reducing storage and bandwidth overhead as highlighted in the comparison table.

Sortable and Time-Embedded

K-ordered with 1-second precision time embedding, enabling chronological sorting without extra database fields, based on the Mongo Object ID algorithm.

Zero Configuration

Works out-of-the-box without machine/data-center IDs or central servers, simplifying deployment in distributed systems as noted in the philosophy.

Lock-Free Performance

Avoids global locks used in UUIDv1/v2, ensuring better concurrency and speed, with benchmarks showing faster generation than UUIDs in multi-CPU environments.

URL-Safe Encoding

Uses base32hex for case-insensitive, sortable string representation that is web-friendly and avoids issues with non-alphanumeric characters in transports.

Cons

Not Cryptographically Secure

IDs are predictable due to reliance on system time and a monotonic counter, making it unsuitable for security-sensitive use cases, as admitted in the notes.

Coarse Time Precision

Limited to 1-second granularity, which may not suffice for applications requiring millisecond or microsecond accuracy in ID timestamps.

Unicity Per Second Limits

Guarantees only up to 16,777,216 unique IDs per second per host/process; high-scale systems could exhaust this, risking collisions under extreme load.

Go-Centric with Ports

Primarily a Go library, and while ports exist for other languages, they may lack the same maturity, documentation, or community support, limiting cross-platform adoption.

Frequently Asked Questions

What is xid?

Target Audience

Go developers building distributed systems, web services, or databases who need efficient, sortable unique identifiers without setup overhead.

Value Proposition

Developers choose xid for its balance of small size, built-in sortability, and zero-configuration design, offering better performance and simplicity compared to UUIDs or Snowflake-like systems.

Use Cases

Best For

Generating sortable primary keys in distributed databases
Adding request IDs to web server logs for tracing
Creating compact, URL-safe identifiers for API resources
Replacing UUIDs in Go applications where smaller, sortable IDs are beneficial
Embedding timestamps in IDs for chronological ordering without extra fields
Building stateless services that need unique IDs without central coordination

Not Ideal For

Applications requiring cryptographically secure, unpredictable IDs (e.g., security tokens or anti-fraud systems)
Systems needing sub-millisecond timestamp precision in IDs for fine-grained event ordering
High-throughput scenarios where a single host/process must generate over 16 million unique IDs per second

Pros & Cons

Pros

Compact and Efficient

At 12 bytes binary and 20 characters string, it's smaller than UUIDs (16 bytes, 36 chars), reducing storage and bandwidth overhead as highlighted in the comparison table.

Sortable and Time-Embedded

K-ordered with 1-second precision time embedding, enabling chronological sorting without extra database fields, based on the Mongo Object ID algorithm.

Zero Configuration

Works out-of-the-box without machine/data-center IDs or central servers, simplifying deployment in distributed systems as noted in the philosophy.

Lock-Free Performance

Avoids global locks used in UUIDv1/v2, ensuring better concurrency and speed, with benchmarks showing faster generation than UUIDs in multi-CPU environments.

URL-Safe Encoding

Uses base32hex for case-insensitive, sortable string representation that is web-friendly and avoids issues with non-alphanumeric characters in transports.

Cons

Not Cryptographically Secure

IDs are predictable due to reliance on system time and a monotonic counter, making it unsuitable for security-sensitive use cases, as admitted in the notes.

Coarse Time Precision

Limited to 1-second granularity, which may not suffice for applications requiring millisecond or microsecond accuracy in ID timestamps.

Unicity Per Second Limits

Guarantees only up to 16,777,216 unique IDs per second per host/process; high-scale systems could exhaust this, risking collisions under extreme load.

Go-Centric with Ports

Primarily a Go library, and while ports exist for other languages, they may lack the same maturity, documentation, or community support, limiting cross-platform adoption.

Frequently Asked Questions

xid

What is xid?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?

xid

What is xid?

Overview

Use Cases

Best For

Not Ideal For

Pros & Cons

Pros

Cons

Frequently Asked Questions

Related Projects

Found a gem we're missing?