The Pearls and Pitfalls of DateTime by Mahmoud Abdelghany

DateTime handling is complex and error-prone, with many edge cases around time zones, formats, and epochs

Time zones are not static - cities/regions can change their time zones, appear or disappear over time, requiring use of time zone databases that need regular updates

Converting everything to UTC is not a complete solution - historical dates still need original time zone context to be interpreted correctly

API design for date/time is challenging - many popular libraries and frameworks handle dates differently (Java Date, C#, Python), leading to compatibility issues

Date/time values can have different epochs (Unix, DOS, Excel etc.), formats (binary vs string), and resolutions (seconds vs microseconds)

Always store both UTC timestamp and original time zone offset to maintain data integrity and auditability

Date parsing and formatting is dangerous - ambiguous formats (MM/DD vs DD/MM), lenient vs strict parsing, and localization issues can cause errors

Time zone databases like IANA need regular updates to handle changes in daylight savings and political time zone modifications

For forensics and legal applications, accurate timestamp handling is critical as it can affect evidence validity

No silver bullet solution exists - proper date/time handling requires understanding the specific use case, testing edge cases, and using appropriate tools/libraries