Added average metric AVG() to default metrics

[vera-liu]

Issue: #804

Done: Added avg to default metrics in models->SqlaTable

needs-review @bkyryliuk @mistercrunch

[bkyryliuk]

s/dbcol.sum/dbcol.avg ?

[vera-liu]

I'm thinking that the condition for dbcol.sum and dbcol.avg are both dbcol.isnum, so it makes sense to use one variable, as long as there's a sum, there can be an avg metrics as well

[bkyryliuk]

dbcol.max and dbcol.min are also in similar relation.
@mistercrunch - should avg be a separate field in the TableColumn ?

[bkyryliuk]

I've talked to Max, please implement a separate checkbox for AVG metric.
User may not expect to add 2 metrics when setting the sum checkbox and will be tricky to explain him if you want to add avg metrics - please select sum.

[bkyryliuk]

it would be great to have a unit test here

[vera-liu]

Do we have tests covering metrics/groupby of db queries? I was trying to look for them but didn't seem to exist core_tests.py

[bkyryliuk]

nope, you'll be a first one if you'll decide to do it

[vera-liu]

Since it will be tests covering all metrics, I'll separate it to another PR ;)

[vera-liu]

Added a new commit, making avg a column for SqlaTable and Druid class @bkyryliuk

[bkyryliuk]

please fix the tests

[vera-liu]

Added migration 😃 @bkyryliuk

[bkyryliuk]

LGTM

[mohadelrezk]

Hi,
I am using latest version of superset (0.24)
but average is not activated as a metric when I create a chart/slice from druid datasource

note: it is available when I load data from csv files directly

[mistercrunch]

You have to create post-aggregations for averages on Druid.