Package xid is a globally unique id generator suited for web scale
Xid is using Mongo Object ID algorithm to generate globally unique ids: https://docs.mongodb.org/manual/reference/object-id/
- 4-byte value representing the seconds since the Unix epoch,
- 3-byte machine identifier,
- 2-byte process id, and
- 3-byte counter, starting with a random value.
The binary representation of the id is compatible with Mongo 12 bytes Object IDs. The string representation is using URL safe base64 for better space efficiency when stored in that form (16 bytes).
UUIDs are 16 bytes (128 bits) and 36 chars as string representation. Twitter Snowflake ids are 8 bytes (64 bits) but require machine/data-center configuration and/or central generator servers. xid stands in between with 12 bytes (96 bits) and a more compact URL-safe string representation (16 chars). No configuration or central generator server is required so it can be used directly in server's code.
Features:
- Size: 12 bytes (96 bits), smaller than UUID, larger than snowflake
- Base64 URL safe encoded by default (16 chars when transported as printable string)
- Non configured, you don't need set a unique machine and/or data center id
- K-ordered
- Embedded time with 1 second precision
- Unicity guaranteed for 16,777,216 (24 bits) unique ids per second and per host/process
Best used with xlog's RequestIDHandler.
References:
- http://www.slideshare.net/davegardnerisme/unique-id-generation-in-distributed-systems
- https://en.wikipedia.org/wiki/Universally_unique_identifier
- https://blog.twitter.com/2010/announcing-snowflake
go get github.com/rs/xid
guid := xid.New()
println(guid.String())
// Output: TYjhW2D0huQoQS3JGet xid embedded info:
guid.Machine()
guid.Pid()
guid.Time()
guid.Counter()All source code is licensed under the MIT License.