Question 1

xid vs UUID: which is better for web APIs?

Accepted Answer

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.

Question 2

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

Accepted Answer

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.

Question 3

Is xid sortable and how does it compare to Snowflake?

Accepted Answer

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.

Question 4

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

Accepted Answer

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.

Question 5

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

Accepted Answer

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.

Question 6

How many xids can I generate per second without collisions?

Accepted Answer

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

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