Data Cardinality in a Distributed DB: Lessons from a Betting App

Cardinality in a distributed database refers to the uniqueness of values in data. Low cardinality means few unique values, while high cardinality indicates many unique values. In the context of distributed databases like CockroachDB, cardinality plays an important role in optimizing performance and ensuring that data is evenly spread across different nodes. Ultimate Tournament, a betting platform for eSports matches, uses CockroachDB to handle large numbers of incoming reads and writes during peak times. By carefully designing keys and indexes, the company avoids creating hot rows or full table scans, which can impact performance across all nodes in a distributed system.