Design Tinder (Matching System)

MySQL: Core Data

CREATE TABLE users (
    user_id         BIGINT PRIMARY KEY AUTO_INCREMENT,
    name            VARCHAR(100),
    birth_date      DATE,
    gender          ENUM('M','F','NB'),
    bio             TEXT,
    photo_urls      JSON,
    last_active     TIMESTAMP,
    latitude        DECIMAL(10,7),
    longitude       DECIMAL(10,7),
    elo_score       FLOAT DEFAULT 1000,
    created_at      TIMESTAMP DEFAULT CURRENT_TIMESTAMP
);

CREATE TABLE preferences (
    user_id         BIGINT PRIMARY KEY,
    gender_pref     SET('M','F','NB'),
    age_min         TINYINT,
    age_max         TINYINT,
    distance_km     SMALLINT DEFAULT 50,
    FOREIGN KEY (user_id) REFERENCES users(user_id)
);

CREATE TABLE matches (
    match_id        BIGINT PRIMARY KEY AUTO_INCREMENT,
    user_id_1       BIGINT,
    user_id_2       BIGINT,
    matched_at      TIMESTAMP DEFAULT CURRENT_TIMESTAMP,
    UNIQUE KEY (user_id_1, user_id_2),
    INDEX idx_user1 (user_id_1, matched_at DESC),
    INDEX idx_user2 (user_id_2, matched_at DESC)
);

Redis: Location & Swipe State

# Geospatial index for proximity queries
Key:    users:geo
Type:   GeoSet
Ops:    GEOADD users:geo {lng} {lat} {user_id}
Query:  GEORADIUS users:geo {lng} {lat} 50 km COUNT 10000

# Swipe history (who has this user swiped on?)
Key:    swiped:{user_id}
Type:   SET (all swiped user_ids — left or right)
Purpose: Filter already-seen profiles from discovery

# Right-swipe tracking (for match detection)
Key:    swiped_right:{user_id}
Type:   SET (user_ids this user swiped right on)

# Pre-computed discovery deck
Key:    deck:{user_id}
Type:   LIST (ordered user_ids for next swipe session)
TTL:    1 hour