Grokking the System Design Interview

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Designing Uber backend

1. What is Uber?

Uber enables its customers to book drivers for taxi rides. Uber drivers use their personal cars to drive customers around. Both customers and drivers communicate with each other through their smartphones using the Uber app.

Try it yourself

Before looking at the solution, try designing it:

Designing Uber (video)

Here is a video discussing how to design Uber:

2. Requirements and Goals of the System

Let’s start with building a simpler version of Uber.

There are two types of users in our system: 1) Drivers 2) Customers.

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Junaid Effendi

· 4 years ago

With DriverLocationHT, if quad tree is updated 15 seconds from the DriverLocationHT, is this DriverLocationHT is getting updated every three seconds? don't we lose information between 3 - 15 seconds, not really worth it may be?

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C

CQ

· 4 years ago

Why do we need to use a push model to notify the user instead of the pull model?

Since the client is getting driver location updates every couple other seconds, the limitations of pull model such as most of the query result being empty and wasted bandwidth are no longer applying.

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evan

· 3 years ago

I get how the problem is similar to the Yelp example, but for the scale at which we're working I don't think creating the Quad-Tree is necessary. Especially because the driver location information is only relevant "right now". There's no need to persist it for future reference. Wouldn't if be sufficient to only store the driver location in-memory using something like memcached? Even if the memcached server went down you could have replicas of it, and only the most recent location of the driver that would be put in memcached would be relevant.

李Li明穎Ming-Ying

李Li明穎Ming-Ying

· 3 years ago

How about Geohash which is more suitable for frequent updates? Lyft also uses it.

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andreachiou88

· a year ago

For this use case, under heading #4 ("Basic System Design"), why didn't we specify a few APIs as we did for the URL shortener use case? is there a guideline for when, in an interview, you need to specify down to parameters what an API should contain?