Description

Yet another snowflake sequence id generator.

Inspired By

This moduled is inspired by:

1. https://developer.twitter.com/en/docs/basics/twitter-ids
2. https://www.callicoder.com/distributed-unique-id-sequence-number-generator/
3. https://www.npmjs.com/package/flake-idgen

How could you implement unique id's over a set of N servers?

why not use GUIDs?

• Mostly because GUIDs are big, and they index badly
• Generated IDs should be sortable by time
• Index size is a key consideration
• If you can’t keep your indexes in memory, you can’t keep your database fast

# solutions

Solution 1:Generate IDs in web application

This approach leaves ID generation entirely up to your application, and not up to the database at all. Implementation: MongoDB’s ObjectId, UUID

Pros1: Each application thread generates IDs independently, minimizing points of failure and contention for ID generation.

Pros2: If you use a timestamp as the first component of the ID, the IDs remain time-sortable.

Cons1: Generally requires more storage space (96 bits or higher) to make reasonable uniqueness guarantees.

Cons2: Some UUID types are completely random and have no natural sort

Solution 2: Generate IDs through dedicated service (Snowflake)

Pros1: Snowflake IDs are 64-bits, half the size of a UUID.

Pros2: Can use time as first component and remain sortable.

Pros3: Distributed system.

Cons1: Would introduce additional complexity.

Solution 3: DB Ticket Servers (flickr database Ticket Servers)

This approach uses a centralized database server to generate unique incrementing IDs. It’s like a centralized auto-increment. This approach is used by Flickr.

Pros1: DBs are well understood and have pretty predictable scaling factors.

Cons1: Can eventually become a write bottleneck.

Cons2: An additional couple of machines.

Cons3: If using a single DB, becomes single point of failure. If using multiple DBs, can no longer guarantee that they are sortable over time.

Solution 4: Sharded system based on postgress schema

Link: https://instagram-engineering.com/sharding-ids-at-instagram-1cf5a71e5a5c

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Why?

This moduled is implemented as a weekend project in order to understand the Twitter Snowflake ID generator. You can find various Snowflake implementation on the net, others were too complicated to understand, So I decided to write a simple and readble one.

How to use

npm install simple-snowflake

javascript

const SnowFlake = require('simple-snowflake');

const snowFlakeGen = new SnowFlake({ epoch: new Date().getTime(), machine: 15, worker: 10 });

const { binary, hex, err } = snowFlakeGen.next();

/*
  binary ==> {
    raw: '0000000000000000000000000000000000000000000111101010000000001010',
    splited: '0000 0000 0000 0000 0000 0000 0000 0000 0000 0000 0001 1110 1010 0000 0000 1010'
  }
  hex ==> 00000000001EA00A
*/

License

This project is licensed under the terms of the MIT license.