Tuesday, June 21, 2022

Sortable UUIDs (GUIDs) with NewId

 Generating sortable Guids using NewId

pros-and-cons of using database-generated integer vs client-generated Guids, and introduce NewId as a way of mitigating some of the downsides of Guids.

phatboyg/NewId: A sequential id generator that works across nodes with no collisions @GitHub

.NET Guid.NewGuid()

NewId is designed to solve a specific problem. It's for when you want a unique ID, but you want them to generally be sortable, and semi-predictable. 


  • be170000-f32d-18db—this is apparently constant across all IDs.
  • de59—this changes with every ID.
  • 08da26f2ad5a—this sometimes changes, and changes gradually.

NewId uses 3 different sources to construct an ID

  • A "worker/process ID". This is constant for a given machine (and can be configured to also include the process ID).
  • A "timestamp". This provides the basic ordering of the ID
  • A "sequence". An incrementing ID.

By combining all 3 together, you can get an ID that is (roughly) orderable, thanks to the timestamp component. By including the worker ID you can have workers independently generate IDS while avoiding collisions. And the use of the "sequence" means you can generate 216-1 IDs per millisecond, per worker:

Guids have caused nearly 99% fragmentation in the (SQL server database) index, whereas the NewIds have caused only a 5% fragmentation. 

javascript - How to create a GUID / UUID - Stack Overflow

All UUID's generated by this library are built with 4 bytes of timestamp and 12 secure random bytes generated with crypto library.

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