westonpace opened a new issue, #7249: URL: https://github.com/apache/arrow-datafusion/issues/7249
### Is your feature request related to a problem or challenge? Postgres supports an optional precision specifier in timestamp literals (e.g. `timestamp (3) '2021-01-01 00:00:00.123'` . The [postgres spec](https://www.postgresql.org/docs/current/datatype-datetime.html) technically only allows 0-6 but given that Arrow timestamps support nanoseconds it would probably be best to support 0-9. ### Describe the solution you'd like For my purposes, It would be sufficient to only support precision values of 0, 3, 6, and 9 (seconds, milliseconds, microseconds, and nanoseconds) though it should be possible to support values that aren't a multiple of 3 since the expectation is that this value is only used for parsing the literal and it is not a constraint on the type at all (e.g. a timestamp(5) could be stored at microsecond resolution as long as the string is parsed correctly). Ideally, output would look like the following: ``` ❯ select arrow_typeof(timestamp (6) '2021-01-01 00:00:00.123456789'); +-------------------------------------------+ | arrow_typeof(Utf8("2021-01-01 00:00:00.123456")) | +-------------------------------------------+ | Timestamp(Microsecond, None) | +-------------------------------------------+ ❯ select arrow_typeof(timestamp (3) '2021-01-01 00:00:00.123456789'); +-------------------------------------------+ | arrow_typeof(Utf8("2021-01-01 00:00:00.123")) | +-------------------------------------------+ | Timestamp(Millisecond, None) | +-------------------------------------------+ ❯ select arrow_typeof(timestamp (0) '2021-01-01 00:00:00.123456789'); +-------------------------------------------+ | arrow_typeof(Utf8("2021-01-01 00:00:00")) | +-------------------------------------------+ | Timestamp(Second, None) | +-------------------------------------------+ ❯ select arrow_typeof(timestamp (9) '2021-01-01 00:00:00.123456789'); +-------------------------------------------+ | arrow_typeof(Utf8("2021-01-01 00:00:00.123456789")) | +-------------------------------------------+ | Timestamp(Nanosecond, None) | +-------------------------------------------+ ``` Example postgres output: https://www.db-fiddle.com/f/oiHdDy1v78mC1zKbCFvWdV/0 ### Describe alternatives you've considered A pretty usable workaround at the moment is to cast: ``` # These should be equivalent timestamp (6) '2021-01-01 00:00:00' arrow_cast(timestamp '2021-01-01 00:00:00', 'Timestamp(Microsecond, None)') ``` Unfortunately, this requires df-specific functions (arrow_cast) and it would also break backwards compatibility with Lance's current SQL parsing. ### Additional context _No response_ -- This is an automated message from the Apache Git Service. To respond to the message, please log on to GitHub and use the URL above to go to the specific comment. To unsubscribe, e-mail: [email protected] For queries about this service, please contact Infrastructure at: [email protected]
