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The ReplacingMergeTree table engine in ClickHouse is designed to automatically manage deduplication of rows by keeping only the latest version of each row based on a specified sorting key, either the most recently inserted row or the one with the highest version number. This feature is particularly useful for maintaining current state tables, such as user profiles or order statuses, where only the latest data is required, rather than a full historical account. The deduplication process occurs during background merge operations, which may result in temporary duplicate rows in query results until merges are completed. Users can enhance control over deduplication by specifying a version column or using a sign column to mark rows as deleted. The choice of ORDER BY and version columns is crucial for ensuring effective deduplication and query performance. For scenarios requiring immediate deduplication, the SELECT FINAL query modifier can be used, although it incurs additional overhead. Alternatively, materialized views can provide an efficient solution for frequently accessed deduplicated data, as they compute the latest state at insert time. The platform Tinybird offers managed services for running ReplacingMergeTree tables, handling merge optimization and infrastructure management, thus allowing users to focus on application logic.