Charts built off Snowflake only support uppercase metric labels

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• I have checked the superset logs for python stacktraces and included it here as text if there are any.
• I have reproduced the issue with at least the latest released version of superset.
• I have checked the issue tracker for the same issue and I haven’t found one similar.

Superset version

0.31.1

Expected results

Chart should render without error when metric is given a non-uppercase label.

Actual results

Chart fails to render when metric is given a non-uppercase label. Stacktrace is as follows:

Traceback (most recent call last):
  File "/home/superset/superset/views/base.py", line 114, in wraps
    return f(self, *args, **kwargs)
  File "/home/superset/superset/views/core.py", line 1229, in explore_json
    samples=samples,
  File "/home/superset/superset/views/core.py", line 1160, in generate_json
    payload = viz_obj.get_payload()
  File "/home/superset/superset/viz.py", line 378, in get_payload
    payload['data'] = self.get_data(df)
  File "/home/superset/superset/viz.py", line 1231, in get_data
    df = self.process_data(df)
  File "/home/superset/superset/viz.py", line 1151, in process_data
    values=self.metric_labels)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/frame.py", line 5303, in pivot_table
    margins_name=margins_name)
  File "/usr/local/lib/python3.6/site-packages/pandas/core/reshape/pivot.py", line 61, in pivot_table
    raise KeyError(i)
KeyError: 'my label'

Steps to reproduce

1. Create a chart (I’ve reproduced this error with bar chart and line chart).
2. Add a metric to the chart under Query > Metrics in the chart UI.
3. Click on the created metric; this will open a new box, and at the top is a place to write a custom label for the metric. Provide the metric a non-uppercase label, e.g. my label.
4. Run the query.

[yuguang]

@yuyuhan0306 Try adding {"connect_args": {"session_parameters": {"QUOTED_IDENTIFIERS_IGNORE_CASE": false}}} to the engine_params of the Snowflake configuration. After that, you should be able to lowercase column names by running SELECT AS statements. I tested this out by running SELECT hospital as "hospital" FROM emory.public.raw_er, which returned a lowercase hospital column.

[yuguang]

@yuyuhan0306 Which branch are you on? If you are not on master, you will need this pull request: https://github.com/apache/incubator-superset/pull/7147