Dynamic time granularity on any datetime column

[mistercrunch]

This allows to apply a datetime alteration expression, defined per database.

If your datetime column is a timestamp, you can use this to group by day, week, or whatever.

[gbrian]

Hi @mistercrunch,

How difficult could be to have the "grain" definition with the datasource definition ?
I mean, can this:
DB_TIME_GRAINS = {

•        'presto': (
  

•            Grain('Time Column', '{ds}'),
  

•            Grain('week', 'date_trunc(week, {ds})'),
  

•            Grain('month', 'date_trunc(month, {ds})'),
  

•        ),
  

•        'mysql': (
  

•            Grain('Time Column', '{ds}'),
  

•            Grain('day', 'DATE({ds})'),
  

•            Grain('week', 'DATE_SUB({ds}, INTERVAL DAYOFWEEK({ds}) - 1 DAY)'),
  

•            Grain('month', 'DATE_SUB({ds}, INTERVAL DAYOFMONTH({ds}) - 1 DAY)'),
  

•        ),
  

•    }
  

be moved as a "Advanced configuration" setting on the datasource form data? In this way will be enough with SQLAlchemy driver to add a new datasource and use this functionality.

Just to confirm, same functionality can be achieve by using expression fields, right ? ofc this way is better! ;)

Any chance to use SQLAlchemy functions ?
http://stackoverflow.com/questions/12019766/how-to-get-month-and-year-from-date-field-in-sqlalchemy
http://stackoverflow.com/questions/1453591/how-to-filter-query-in-sqlalchemy-by-year-datetime-column

Thanks

[mistercrunch]

At the datasource level it would have to be defined for each datasource, which is redundant, though maybe the datasource could eventually offer a whitelist/blacklist configuration.

From my understanding I don't think SqlAlchemy functions are reliable or have any guarantees that they work across dialects...

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