diff --git a/caravel/migrations/versions/c611f2b591b8_dim_spec.py b/caravel/migrations/versions/c611f2b591b8_dim_spec.py
new file mode 100644
index 00000000000..58d50871c1c
--- /dev/null
+++ b/caravel/migrations/versions/c611f2b591b8_dim_spec.py
@@ -0,0 +1,22 @@
+"""dim_spec
+
+Revision ID: c611f2b591b8
+Revises: ad4d656d92bc
+Create Date: 2016-11-02 17:36:04.970448
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'c611f2b591b8'
+down_revision = 'ad4d656d92bc'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.add_column('columns', sa.Column('dimension_spec_json', sa.Text(), nullable=True))
+
+
+def downgrade():
+    op.drop_column('columns', 'dimension_spec_json')
diff --git a/caravel/models.py b/caravel/models.py
index d5ccf88721d..8494d4716a8 100644
--- a/caravel/models.py
+++ b/caravel/models.py
@@ -1884,6 +1884,8 @@ class DruidDatasource(Model, AuditMixinNullable, Queryable):
         all_metrics = []
         post_aggs = {}
 
+        columns_dict = {c.column_name: c for c in self.columns}
+
         def recursive_get_fields(_conf):
             _fields = _conf.get('fields', [])
             field_names = []
@@ -1931,9 +1933,19 @@ class DruidDatasource(Model, AuditMixinNullable, Queryable):
                 "Access to the metrics denied: " + ', '.join(rejected_metrics)
             )
 
+        # the dimensions list with dimensionSpecs expanded
+        dimensions = []
+        groupby = [gb for gb in groupby if gb in columns_dict]
+        for column_name in groupby:
+            col = columns_dict.get(column_name)
+            dim_spec = col.dimension_spec
+            if dim_spec:
+                dimensions.append(dim_spec)
+            else:
+                dimensions.append(column_name)
         qry = dict(
             datasource=self.datasource_name,
-            dimensions=groupby,
+            dimensions=dimensions,
             aggregations=aggregations,
             granularity=DruidDatasource.granularity(
                 granularity,
@@ -2242,6 +2254,7 @@ class DruidColumn(Model, AuditMixinNullable):
     min = Column(Boolean, default=False)
     filterable = Column(Boolean, default=False)
     description = Column(Text)
+    dimension_spec_json = Column(Text)
 
     def __repr__(self):
         return self.column_name
@@ -2250,6 +2263,11 @@ class DruidColumn(Model, AuditMixinNullable):
     def isnum(self):
         return self.type in ('LONG', 'DOUBLE', 'FLOAT', 'INT')
 
+    @property
+    def dimension_spec(self):
+        if self.dimension_spec_json:
+            return json.loads(self.dimension_spec_json)
+
     def generate_metrics(self):
         """Generate metrics based on the column metadata"""
         M = DruidMetric  # noqa
diff --git a/caravel/views.py b/caravel/views.py
index fe4c0c12304..28e81041e6e 100755
--- a/caravel/views.py
+++ b/caravel/views.py
@@ -356,8 +356,9 @@ appbuilder.add_view_no_menu(TableColumnInlineView)
 class DruidColumnInlineView(CompactCRUDMixin, CaravelModelView):  # noqa
     datamodel = SQLAInterface(models.DruidColumn)
     edit_columns = [
-        'column_name', 'description', 'datasource', 'groupby',
-        'count_distinct', 'sum', 'min', 'max']
+        'column_name', 'description', 'dimension_spec_json', 'datasource',
+        'groupby', 'count_distinct', 'sum', 'min', 'max']
+    add_columns = edit_columns
     list_columns = [
         'column_name', 'type', 'groupby', 'filterable', 'count_distinct',
         'sum', 'min', 'max']
@@ -374,9 +375,23 @@ class DruidColumnInlineView(CompactCRUDMixin, CaravelModelView):  # noqa
         'min': _("Min"),
         'max': _("Max"),
     }
+    description_columns = {
+        'dimension_spec_json': utils.markdown(
+            "this field can be used to specify  "
+            "a `dimensionSpec` as documented [here]"
+            "(http://druid.io/docs/latest/querying/dimensionspecs.html). "
+            "Make sure to input valid JSON and that the "
+            "`outputName` matches the `column_name` defined "
+            "above.",
+            True),
+    }
 
     def post_update(self, col):
         col.generate_metrics()
+        utils.validate_json(col.dimension_spec_json)
+
+    def post_add(self, col):
+        self.post_update(col)
 
 appbuilder.add_view_no_menu(DruidColumnInlineView)
 
@@ -707,11 +722,11 @@ class DruidClusterModelView(CaravelModelView, DeleteMixin):  # noqa
         'broker_endpoint': _("Broker Endpoint"),
     }
 
-    def pre_add(self, db):
-        utils.merge_perm(sm, 'database_access', db.perm)
+    def pre_add(self, cluster):
+        utils.merge_perm(sm, 'database_access', cluster.perm)
 
-    def pre_update(self, db):
-        self.pre_add(db)
+    def pre_update(self, cluster):
+        self.pre_add(cluster)
 
 
 if config['DRUID_IS_ACTIVE']:
diff --git a/caravel/viz.py b/caravel/viz.py
index 28aae15e949..7b34daa5cac 100755
--- a/caravel/viz.py
+++ b/caravel/viz.py
@@ -1034,7 +1034,6 @@ class NVD3TimeSeriesViz(NVD3Viz):
     def get_df(self, query_obj=None):
         form_data = self.form_data
         df = super(NVD3TimeSeriesViz, self).get_df(query_obj)
-
         df = df.fillna(0)
         if form_data.get("granularity") == "all":
             raise Exception("Pick a time granularity for your time series")
diff --git a/tests/core_tests.py b/tests/core_tests.py
index 111f0d351f1..a57f244ac03 100644
--- a/tests/core_tests.py
+++ b/tests/core_tests.py
@@ -10,10 +10,8 @@ import json
 import io
 import random
 import unittest
-from datetime import datetime
 
 from flask import escape
-from flask_appbuilder.security.sqla import models as ab_models
 
 from caravel import db, models, utils, appbuilder, sm, jinja_context
 from caravel.views import DatabaseView
diff --git a/tests/druid_tests.py b/tests/druid_tests.py
index 7a16a666cbe..f409cfa4cf2 100644
--- a/tests/druid_tests.py
+++ b/tests/druid_tests.py
@@ -48,16 +48,16 @@ GB_RESULT_SET = [
     "version": "v1",
     "timestamp": "2012-01-01T00:00:00.000Z",
     "event": {
-      "name": 'Canada',
-      "sum__num": 12345678,
+      "dim1": 'Canada',
+      "metric1": 12345678,
     }
   },
   {
     "version": "v1",
     "timestamp": "2012-01-01T00:00:00.000Z",
     "event": {
-      "name": 'USA',
-      "sum__num": 12345678 / 2,
+      "dim1": 'USA',
+      "metric1": 12345678 / 2,
     }
   },
 ]
@@ -121,26 +121,26 @@ class DruidTests(CaravelTestCase):
         url = (
             '/caravel/explore_json/druid/{}/?viz_type=table&granularity=one+day&'
             'druid_time_origin=&since=7+days+ago&until=now&row_limit=5000&'
-            'include_search=false&metrics=count&groupby=name&flt_col_0=dim1&'
+            'include_search=false&metrics=count&groupby=dim1&flt_col_0=dim1&'
             'flt_op_0=in&flt_eq_0=&slice_id=&slice_name=&collapsed_fieldsets=&'
             'action=&datasource_name=test_datasource&datasource_id={}&'
             'datasource_type=druid&previous_viz_type=table&'
             'force=true'.format(datasource_id, datasource_id))
         resp = self.get_json_resp(url)
-        self.assertEqual("Canada", resp['data']['records'][0]['name'])
+        self.assertEqual("Canada", resp['data']['records'][0]['dim1'])
 
         # two groupby
         url = (
             '/caravel/explore_json/druid/{}/?viz_type=table&granularity=one+day&'
             'druid_time_origin=&since=7+days+ago&until=now&row_limit=5000&'
-            'include_search=false&metrics=count&groupby=name&'
-            'flt_col_0=dim1&groupby=second&'
+            'include_search=false&metrics=count&groupby=dim1&'
+            'flt_col_0=dim1&groupby=dim2d&'
             'flt_op_0=in&flt_eq_0=&slice_id=&slice_name=&collapsed_fieldsets=&'
             'action=&datasource_name=test_datasource&datasource_id={}&'
             'datasource_type=druid&previous_viz_type=table&'
             'force=true'.format(datasource_id, datasource_id))
         resp = self.get_json_resp(url)
-        self.assertEqual("Canada", resp['data']['records'][0]['name'])
+        self.assertEqual("Canada", resp['data']['records'][0]['dim1'])
 
     def test_druid_sync_from_config(self):
         CLUSTER_NAME = 'new_druid'