# Uber

* [Use cases](#use-cases)
* [Functional requirements](#functional-requirements)
* [Non-functional requirements](#non-functional-requirements)
  * [High performance](#high-performance)
  * [Scalable](#scalable)
* [Real world](#real-world)
* [References](#references)
* [Appendix](#appendix) - [Past chart](#past-chart)
  * [TODO](#todo)

## Use cases

* Real time cab booking service like Uber, Lyft, Bolt.
* Real time hotel / restaurant search like Yelp.
* Target shoppers nearing a certain store for a marketing promotion.
* Hyper-local delivery system — dispatch delivery agents for restaurant order like Uber Eats.

## Functional requirements

* Given a location by a client or user, our service should figure out certain number of nearby locations.
  * NN: Given a location, find the nearest k points
  * Range query: Retrieve all points within a specific spatial range.
* Update location

## Non-functional requirements

### High performance

* The location should be accurate so that the delay in update should response ≤ 200 milliseconds.
* We need to support 50000 read queries per second & 10000 write queries per second.

### Scalable

* Our service is used world wide.
* As users grow in our system, the system should scale linearly without adding much burden.

## Real world

* [Unique GeoId in Twitter](https://blog.twitter.com/engineering/en_us/a/2010/woeids-in-twitters-trends.html)
* [TODO: Uber Marketplace: Location Serving & Storage in the Uber Marketplace](https://www.youtube.com/watch?v=AzptiVdUJXg\&ab_channel=UberEngineering)

## References

* [R tree / KD - tree](https://blog.mapbox.com/a-dive-into-spatial-search-algorithms-ebd0c5e39d2a)
* [Geohash vs S2 vs H3](https://dev.to/phm200/the-problem-of-nearness-part-2-a-solution-with-s2-23gm)
* [Redis data model based basic algorithm for finding available drivers](https://www.youtube.com/watch?v=cSFWlF96Sds)
* [四火唠嗑](https://www.raychase.net/6312)
* [Indepth system design discussion](https://kousiknath.medium.com/system-design-design-a-geo-spatial-index-for-real-time-location-search-10968fe62b9c)

## Appendix

* A great percentage of the below post comes from this blog <https://kousiknath.medium.com/system-design-design-a-geo-spatial-index-for-real-time-location-search-10968fe62b9c>

**Past chart**

![Schema design](https://github.com/DreamOfTheRedChamber/system-design-interviews/blob/master/scenario_locationBased/images/location_mySQL.jpg)

![Report design](/files/-Mk8h-_uxtghF5SDK6u1)

![Storage design](/files/-Mk8h-_vktwPhsBBWh60)

#### TODO

* Uber architecture and system design: <https://medium.com/nerd-for-tech/uber-architecture-and-system-design-e8ac26690dfc>


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