Cannot run queries in SQL Lab with a DB that has timestamps

[fatruchir]

Running a simple select * query on a DB table and getting an error: DatetimeTZDtype' object has no attribute 'char'

• I have checked the superset logs for python stacktraces and included it here as text if any

Traceback (most recent call last):
  File "/Users/ruchir/venv/lib/python2.7/site-packages/superset/views/core.py", line 2076, in sql_json
    query_id=query_id, return_results=True)
  File "/Users/ruchir/venv/lib/python2.7/site-packages/celery/local.py", line 188, in __call__
    return self._get_current_object()(*a, **kw)
  File "/Users/ruchir/venv/lib/python2.7/site-packages/celery/app/task.py", line 428, in __call__
    return self.run(*args, **kwargs)
  File "/Users/ruchir/venv/lib/python2.7/site-packages/superset/sql_lab.py", line 91, in get_sql_results
    ctask, query_id, return_results, store_results)
  File "/Users/ruchir/venv/lib/python2.7/site-packages/superset/sql_lab.py", line 233, in execute_sql
    'columns': cdf.columns if cdf.columns else [],
  File "/Users/ruchir/venv/lib/python2.7/site-packages/superset/dataframe.py", line 108, in columns
    col_db_type = self.db_type(self.__df.dtypes[col])
  File "/Users/ruchir/venv/lib/python2.7/site-packages/superset/dataframe.py", line 55, in db_type
    return cls.type_map.get(dtype.char)
AttributeError: 'DatetimeTZDtype' object has no attribute 'char'

• I have reproduced the issue with at least the latest released version of superset
  Yes
• I have checked the issue tracker for the same issue and I haven't found one similar
  Found this: Failure while pulling clickhouse table with datetime (DatetimeTZDtype has no attribute 'char') #2791 but does not address how to deal with situation when the DB table already exists

Superset version

0.19.1

Expected results

Should return result of SQL query

Actual results

Getting Error: 'DatetimeTZDtype' object has no attribute 'char'

Steps to reproduce

Run any query on a DB which has a timestamptz column type

[xrmx]

Still this looks very much like a duplicate of #2791. No need to track the same issue twice

[fabianmenges]

This should be fixed #2937

[fatruchir]

Still getting this issue after #2937 was merged

[fatruchir]

Trying to query a PostgreSQL DB

[mistercrunch]

Notice: this issue has been closed because it has been inactive for 200 days. Feel free to comment and request for this issue to be reopened.