Package xid is a globally unique id generator library, ready to safely be used directly in your server code.
Xid uses the Mongo Object ID algorithm to generate globally unique ids with a different serialization (base32hex) to make it shorter when transported as a string: https://docs.mongodb.org/manual/reference/object-id/
The binary representation of the id is compatible with Mongo 12 bytes Object IDs. The string representation is using base32hex (w/o padding) for better space efficiency when stored in that form (20 bytes). The hex variant of base32 is used to retain the sortable property of the id.
Xid doesn't use base64 because case sensitivity and the 2 non alphanum chars may be an
issue when transported as a string between various systems. Base36 wasn't retained either
because 1/ it's not standard 2/ the resulting size is not predictable (not bit aligned)
and 3/ it would not remain sortable. To validate a base32 xid
, expect a 20 chars long,
all lowercase sequence of a
to v
letters and 0
to 9
numbers ([0-9a-v]{20}
).
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 (20 chars). No configuration or central generator server is required so it can be used directly in server's code.
Name | Binary Size | String Size | Features |
---|---|---|---|
UUID | 16 bytes | 36 chars | configuration free, not sortable |
shortuuid | 16 bytes | 22 chars | configuration free, not sortable |
Snowflake | 8 bytes | up to 20 chars | needs machine/DC configuration, needs central server, sortable |
MongoID | 12 bytes | 24 chars | configuration free, sortable |
xid | 12 bytes | 20 chars | configuration free, sortable |
Features:
Best used with zerolog's RequestIDHandler.
Notes:
References:
go get github.com/rs/xid
guid := xid.New()
println(guid.String())
// Output: 9m4e2mr0ui3e8a215n4g
Get xid
embedded info:
guid.Machine()
guid.Pid()
guid.Time()
guid.Counter()
Benchmark against Go Maxim Bublis's UUID.
BenchmarkXID 20000000 91.1 ns/op 32 B/op 1 allocs/op
BenchmarkXID-2 20000000 55.9 ns/op 32 B/op 1 allocs/op
BenchmarkXID-4 50000000 32.3 ns/op 32 B/op 1 allocs/op
BenchmarkUUIDv1 10000000 204 ns/op 48 B/op 1 allocs/op
BenchmarkUUIDv1-2 10000000 160 ns/op 48 B/op 1 allocs/op
BenchmarkUUIDv1-4 10000000 195 ns/op 48 B/op 1 allocs/op
BenchmarkUUIDv4 1000000 1503 ns/op 64 B/op 2 allocs/op
BenchmarkUUIDv4-2 1000000 1427 ns/op 64 B/op 2 allocs/op
BenchmarkUUIDv4-4 1000000 1452 ns/op 64 B/op 2 allocs/op
Note: UUIDv1 requires a global lock, hence the performance degradation as we add more CPUs.
All source code is licensed under the MIT License.
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