Support TIMESTAMP_NS, TIMESTAMP_MS & TIMESTAMP_S types

[JelteF]

DuckDB has timestamp types with different precisions. We should support conversion from/to those types. TIMESTAMP_NS is probably the most challenging, since postgres does not have a native timestamp type with nanosecond precision. It seems better to truncate/round the nanoseconds to microseconds though than to not support them at all.

Related to #228, which tracks adding TIMESTAMP WITH TIME ZONE.

[destrex271]

Hi @JelteF , Picking this up.

[JelteF]

@destrex271 are you still expecting to submit a PR for this?

[destrex271]

@destrex271 are you still expecting to submit a PR for this?

Yes, just got stuck in some other stuff. Will try to raise a pr asap

[destrex271]

For conversion from lets say TIMESTAMP_MS to TIMESTAMP we can abstract it in the TIMESTAMP type in postgres, but to convert it back to the original duckdb type, it might get a little hard to manage with this approach.

Should we create a new type/datum like TIMESTAMP_MS for pg as well?