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    SYSTEM-DESIGN
    advanced

    Consistent Hashing

    Software Engineer path · lesson 77 of 99

    Consistent Hashing Ring

    Load Balancing
    3 Servers
    6 Keys
    Server D position:
    Watch how keys redistribute when servers change
    Total Keys
    6
    in system
    Keys Moved
    0
    during scaling
    Rebalance %
    0%
    vs 100% traditional
    Stable Keys
    6
    unchanged
    0°
    90°
    180°
    270°
    Hash Ring
    360° Space
    Server A0°
    Server B120°
    Server C240°
    K1
    → B
    K2
    → B
    K3
    → C
    K4
    → C
    K5
    → A
    K6
    → A
    Server A(2 keys)
    Server B(2 keys)
    Server C(2 keys)
    ServerPositionAssigned KeysLoad
    Server A
    		0°K5, K6
    33%
    Server B
    		120°K1, K2
    33%
    Server C
    		240°K3, K4
    33%

    Find a key’s server

    Sequence

    Order how a consistent-hash ring places and looks up a key.

    Tap a piece, then tap where it goes — or drag it. Tap the tray to take one back.

    1. 1Drop a step here
    2. 2Drop a step here
    3. 3Drop a step here
    4. 4Drop a step here
    5. 5Drop a step here
    5 pieces left to place

    Test your knowledge

    21 questions
    Question 1 of 21
    Score: 0

    In a Consistent Hashing ring, what happens to the keys stored on Server C if a new Server D is placed between Server B and Server C?

    Interview Questions

    Amazon
    Discord
    Netflix
    Amazon
    Uber
    Meta
    Discord
    Cloudflare
    Stripe

    References & Further Reading

    What is Consistent Hashing and Where is it used?YouTube · Gaurav Sen
    video
    Consistent hashingWikipedia
    article
    Hash tableWikipedia
    article
    phoenixtype/system-design-interview-prepGitHub
    docs
    All System Design topics

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