Default time_zone config to None

[alamb]

@alamb With this implementation, yes. To me the logical solution is to allow the time_zone config option to be an Option (and default to None) and fix any existing usage to handle that ... or to detect when the time_zone config option is '' and handle that in the same manner ('' -> None tz)

Originally posted by @Omega359 in #18017 (comment)

[Xuanwo]

Seems to be a good first issue for me, let me take a look on this.

[Xuanwo]

take

[Omega359]

I happened to work on this and left the default as

pub time_zone: Option<String>, default = Some("+00:00".into())

I'm not sure whether the default should be None (slight change in behaviour) or Some("+00:00".into()).

Leaning towards the former but the doc on that config option points to it being used in extract .. but I think extract sql now is delegated to date_part which couldn't have used the timezone before since until recently it didn't have access to ConfigOptions ... so that is likely something that should be fixed in another PR

[Omega359]

Filed #18228 for the extract/date_part issue uncovered in the above comment.

[Omega359]

This issue can be closed with #18359 @alamb

[alamb]

Thanks @Omega359