# Once v1.3.0 - Table of Contents

> An Ecto type for locally unique 64-bits IDs generated by multiple Elixir nodes

## Pages

- [Once](readme.md)
- [LICENSE](license.md)
- [Changelog](changelog.md)
- [Migration Guide](migration.md)

## Modules

- [Once](Once.md): Once is an Ecto type for locally unique (unique within your domain or application) 64-bit IDs generated by multiple Elixir nodes. Locally unique IDs make it easier to keep things separated, simplify caching and simplify inserting related things (because you don't have to wait for the database to return the ID).
- [Once.Prefixed](Once.Prefixed.md): > #### DEPRECATED! Use `Once` directly {: .warning}
>
> This module exists for backward compatibility. New code should use `Once` directly with the `:prefix` option instead. All functionality is identical.

