Amazon Interview Question for Data Engineers


Country: India
Interview Type: In-Person




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Couple of doubts
1. Is date range non overlapping and sorted?
2. Is visitor/date file has record sorted by date?

- Progu November 02, 2018 | Flag Reply
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Let me do it using mapreduce instead of spark, I don't know much of spark. I would assume the concept is similar though.

file1: <startDate endDate>
1 5
8 20
file2: <date visitor>
2 5
3 8
10 120

So answer should be 8-20 since in that date range we have max visitor.

Assumption : since file1 just has ranges it should be a small file and can be loaded into the distributed cache of hadoop.

Now execute map code for file2, the code should do following :
1) read file2 and for each date , see which range it belongs to from the distributed cache and increment the counter for that time range.
eg
for 2 increment counter for 1_5
for 3 increment counter for 1_5
for 10 increment counter for 8_20
3) output <range , counter> as map output
4) In reduce add all the counters for every range.

Also - we need to add total order sorting so that overall output of all reducers are sorted.

- kabs November 24, 2018 | Flag Reply


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