System Design · Senior · Question 55 of 75

How are metrics with billions of points stored cheaply?

✓Correct answer: In a time-series database with compression, retention policies and downsampling of old data into coarser aggregates
2In one JSON file per metric
3In the browser

Explanation

Recent data stays high-resolution; older data is rolled up (e.g. 1-minute → 1-hour) to keep queries fast.

Further reading

Wikipedia: Time series database ↗

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