How to convert dates to Unix timestamps in ClickHouse ®

Converting dates to Unix timestamps in ClickHouse is facilitated by the toUnixTimestamp() function, which transforms Date, DateTime, or String values into integers representing seconds since the Unix epoch starting on January 1, 1970, at midnight UTC. This function is valuable for building APIs requiring epoch seconds, exporting data to systems storing timestamps as integers, or performing time-based calculations. The function accepts various input types and returns a UInt32 value, with Date and Date32 handling being straightforward, while DateTime and DateTime64 maintain precision down to seconds. String inputs must match expected datetime formats, though they perform slower than native datetime types. The function's signature allows an optional timezone parameter, crucial for consistent results, especially when session and data timezones differ. Handling time zones correctly avoids conversion errors, and storing timestamps in UTC is recommended to prevent daylight saving time issues. Pre-computing Unix timestamps in production systems, using materialized views, or default expressions can improve performance while dealing with future dates beyond 2038 necessitates using toUnixTimestamp64() due to UInt32 overflow. Tinybird provides a managed ClickHouse platform supporting real-time analytics APIs, allowing developers to focus on application features without managing infrastructure, with Unix timestamps enhancing performance through better compression, indexing, and SIMD optimizations.