Candidatei-me online. O processo levou 3 semanas. Fui entrevistado pela MachineMetrics em jul. de 2021
Entrevista
Interview Process:
1. Phone Screen
2. Coding Interview
3. System Design
For each step there are some basic introductory questions about background and experience and why you might be a good fit for the company.
Technical screen questions in first phone interview like:
What are some differences between NoSQL and relational databases?
What is Redis?
What is MongoDB?
Name 3 REST HTTP verbs
What is a left outer join?
Perguntas de entrevista [2]
Pergunta 1
Given a JSON file containing an array of objects that represent machine events with the following properties:
{
companyId
machineId
timestamp
type
subtype
key
value
}
Question: How long was the machine ACTIVE during the 14:00 hour?
MachineMetrics
MachineMetrics is an Industrial IoT SaaS company, which basically means that we connect to factory equipment and stream data into the cloud in real time sometimes down to the millisecond level of sampling. We do some in-stream processing and use a variety of database technologies to make this scalable and performant. The data ultimately lands in our cloud (AWS, but not important), and we use it to inform customer-facing applications that provide real-time machine monitoring, in depth reporting and analytics, and advanced applications, such as predictive algorithms that can stop a machine from machining right before critical failure.
Automated Workflow System
We'd like to build an automated workflow system that can take user-defined logic to fire actions both internal and external to the product. Walk us through how you might approach building out this system, both on the frontend/in the app itself, as well as on the API side and backend servers etc. Some examples of what we'd like to be able to configure are seen below.
Example A: When my machine is idle for more than 5 minutes, send a text message and email to the maintenance department
Example B: When the machine spindle speed exceeds a certain threshold OR the 5-minute average spindle speed is above a threshold, reject all parts made within a 10 minute window and send a web hook to our QA software.