Add set_system_time function

[radomird]

Closes #31

I've added a new file with set_system_time function that will set a configuration parameter on the db called user_defined.system_time and fill in the desired value. The versioning function will then try to use this config parameter to set the time_stamp_to_use.

• added new function ✅
• updated versioning_function and versioning_function_no_checks too use the new config parameter ✅
• updated README ✅
• add tests ✅

[radomird]

Hi @paolochiodi I've tried to implement the requested missing feature. Could you please take a look if I'm heading in the right direction?

Thanks.

[simoneb]

@paolochiodi can you please take a look at this PR? we forgot about it

[dzolo]

Nice missing feature. I would suggest to use datetime format YYYY-MM-DD HH24:MI:SS.US in order to be capable to set precise time.

It would be also nice to have timezone support (as in original support) but this will be more work to be done as TO_TIMESTAMP does not support TZ. Maybe cast to timestamp with time zone could be used instead of TO_TIMESTAMP?

[radomird]

@dzolo thanks for the suggestion, adding ms portion to the timestamp is not a bad idea. I will update the date/time format.

Regarding the Timezone support - would be a nice addition, however, I would probably open a feature request issue and that can be tackled in a separate PR, in order not to make this PR more complex than it needs to be.

[radomird]

Support for milliseconds and microseconds added. They are both optional.

@dzolo a review of the PR would be appreciated 😉

[simoneb]

a couple of comments but overall LGTM, nice job 👌