diff --git a/caravel/migrations/versions/6113409d871f_.py b/caravel/migrations/versions/6113409d871f_.py
new file mode 100644
index 000000000000..71ca91cf80d1
--- /dev/null
+++ b/caravel/migrations/versions/6113409d871f_.py
@@ -0,0 +1,19 @@
+"""empty message
+
+Revision ID: 6113409d871f
+Revises: ('c3a8f8611885', 'b4a0abe21630')
+Create Date: 2016-04-28 17:32:51.688497
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = '6113409d871f'
+down_revision = ('c3a8f8611885', 'b4a0abe21630')
+
+
+def upgrade():
+    pass
+
+
+def downgrade():
+    pass
diff --git a/caravel/migrations/versions/b4a0abe21630_post_aggs.py b/caravel/migrations/versions/b4a0abe21630_post_aggs.py
new file mode 100644
index 000000000000..fd8d48ff3921
--- /dev/null
+++ b/caravel/migrations/versions/b4a0abe21630_post_aggs.py
@@ -0,0 +1,31 @@
+"""post_aggs
+
+Revision ID: b4a0abe21630
+Revises: 430039611635
+Create Date: 2016-02-10 15:16:58.953042
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'b4a0abe21630'
+down_revision = '430039611635'
+
+from alembic import op
+import sqlalchemy as sa
+
+
+def upgrade():
+    op.create_table('post_aggregators',
+        sa.Column('id', sa.Integer(), nullable=False),
+        sa.Column('name', sa.String(length=512), nullable=True),
+        sa.Column('verbose_name', sa.String(length=1024), nullable=True),
+        sa.Column('datasource_name', sa.String(length=250), nullable=True),
+        sa.Column('json', sa.Text(), nullable=True),
+        sa.Column('description', sa.Text(), nullable=True),
+        sa.ForeignKeyConstraint(['datasource_name'], ['datasources.datasource_name'], ),
+        sa.PrimaryKeyConstraint('id')
+    )
+
+
+def downgrade():
+    op.drop_table('post_aggregators')
diff --git a/caravel/models.py b/caravel/models.py
index 619682a12be4..8e7a92fb4101 100644
--- a/caravel/models.py
+++ b/caravel/models.py
@@ -5,6 +5,7 @@
 from __future__ import unicode_literals
 
 import functools
+import itertools
 import json
 import logging
 import textwrap
@@ -24,6 +25,9 @@
 from pydruid.client import PyDruid
 from flask.ext.appbuilder.models.decorators import renders
 from pydruid.utils.filters import Dimension, Filter
+from pydruid.utils.postaggregator import Postaggregator
+from pydruid.utils.postaggregator import Const as ConstPostaggregator
+from pydruid.utils.postaggregator import Field as FieldPostaggregator
 from six import string_types
 from sqlalchemy import (
     Column, Integer, String, ForeignKey, Text, Boolean, DateTime, Date,
@@ -907,8 +911,16 @@ class DruidDatasource(Model, AuditMixinNullable, Queryable):
 
     @property
     def metrics_combo(self):
+        # Treat post aggregators as one kind of metrics
+        # TODO: Deal with name conflict between metrics and post_aggregators
         return sorted(
             [(m.metric_name, m.verbose_name) for m in self.metrics],
+            key=lambda x: x[1]) + self.post_aggregators_combo
+
+    @property
+    def post_aggregators_combo(self):
+        return sorted(
+            [(m.name, m.verbose_name) for m in self.post_aggregators],
             key=lambda x: x[1])
 
     @property
@@ -1012,6 +1024,40 @@ def sync_to_db(cls, name, cluster):
             col_obj.datasource = datasource
             col_obj.generate_metrics()
 
+    @classmethod
+    def get_metrics_dependencies(cls, post_aggregation):
+        post_agg_dict = post_aggregation.post_aggregator if isinstance(post_aggregation,
+                                                                       Postaggregator) else post_aggregation
+        if post_agg_dict.get('type') == 'fieldAccess':
+            return [post_agg_dict['fieldName']]
+
+        if post_agg_dict.get('type') == 'arithmetic':
+            fields = post_agg_dict.get('fields')
+            if fields:
+                return list(set(itertools.chain(*[cls.get_metrics_dependencies(field) for field in fields])))
+
+        return []
+
+    @classmethod
+    def get_post_aggregator(cls, params_json):
+        try:
+            params = json.loads(params_json)
+        except Exception:
+            # TODO error messages
+            raise
+
+        obj = None
+        _type = params.get('type')
+        name = params.get('name')
+        if _type == 'arithmetic':
+            obj = Postaggregator(params.get('fn'), params.get('fields'), name)
+        elif _type == 'constant':
+            obj = ConstPostaggregator(params.get('value'), name)
+        elif _type == 'fieldAccess':
+            obj = FieldPostaggregator(params.get('fieldName'))
+
+        return obj
+
     def query(  # druid
             self, groupby, metrics,
             granularity,
@@ -1038,10 +1084,22 @@ def query(  # druid
         to_dttm = to_dttm.replace(tzinfo=config.get("DRUID_TZ"))
 
         query_str = ""
+
+        # TODO: Deal with name conflict between metrics and post_aggregators
+        post_aggregators = {
+            m.name: self.get_post_aggregator(m.json)
+            for m in self.post_aggregators if m.name in metrics
+        }
+
+        metrics_dependencies = list(
+            set(itertools.chain(*[self.get_metrics_dependencies(agg)
+                                  for agg in post_aggregators.values()])) - set(metrics)
+        )
         aggregations = {
             m.metric_name: m.json_obj
-            for m in self.metrics if m.metric_name in metrics
+            for m in self.metrics if m.metric_name in metrics + metrics_dependencies
         }
+
         granularity = granularity or "all"
         if granularity != "all":
             granularity = utils.parse_human_timedelta(
@@ -1057,6 +1115,7 @@ def query(  # druid
             datasource=self.datasource_name,
             dimensions=groupby,
             aggregations=aggregations,
+            post_aggregations=post_aggregators,
             granularity=granularity,
             intervals=from_dttm.isoformat() + '/' + to_dttm.isoformat(),
         )
@@ -1163,6 +1222,7 @@ def query(  # druid
         cols += [col for col in groupby if col in df.columns]
         cols += [col for col in metrics if col in df.columns]
         cols += [col for col in df.columns if col not in cols]
+        cols = [col for col in cols if col not in metrics_dependencies]
         df = df[cols]
         return QueryResult(
             df=df,
@@ -1341,6 +1401,19 @@ def generate_metrics(self):
                 session.commit()
 
 
+class DruidPostAggregator(Model):
+    __tablename__ = 'post_aggregators'
+    id = Column(Integer, primary_key=True)
+    name = Column(String(512))
+    verbose_name = Column(String(1024))
+    datasource_name = Column(
+        String(250),
+        ForeignKey('datasources.datasource_name'))
+    datasource = relationship('DruidDatasource', backref='post_aggregators')
+    json = Column(Text)
+    description = Column(Text)
+
+
 class FavStar(Model):
     __tablename__ = 'favstar'
 
diff --git a/caravel/panoramix/static/widgets/viz_helloworld.js b/caravel/panoramix/static/widgets/viz_helloworld.js
new file mode 100644
index 000000000000..142054927e4e
--- /dev/null
+++ b/caravel/panoramix/static/widgets/viz_helloworld.js
@@ -0,0 +1,19 @@
+px.registerViz('helloworld', function(slice) {
+
+  function refresh() {
+      $('#code').attr('rows', '15')
+      $.getJSON(slice.jsonEndpoint(), function(payload) {
+        slice.container.html(
+          '<h1>HELLOW '+ payload.form_data.username +' !!!</h1>');
+        console.log(payload);
+        slice.done();
+      })
+      .fail(function(xhr) {
+          slice.error(xhr.responseText);
+        });
+      };
+  return {
+    render: refresh,
+    resize: refresh,
+  };
+});
diff --git a/caravel/views.py b/caravel/views.py
index 6d6ef5d7d7d7..37037fbbc88d 100644
--- a/caravel/views.py
+++ b/caravel/views.py
@@ -170,6 +170,19 @@ class DruidMetricInlineView(CompactCRUDMixin, CaravelModelView):  # noqa
 appbuilder.add_view_no_menu(DruidMetricInlineView)
 
 
+class DruidPostAggregatorInlineView(CompactCRUDMixin, CaravelModelView):
+    datamodel = SQLAInterface(models.DruidPostAggregator)
+    list_columns = ['name', 'verbose_name']
+    edit_columns = [
+        'name', 'description', 'verbose_name', 'datasource', 'json']
+    add_columns = edit_columns
+    page_size = 500
+    validators_columns = {
+        'json': [validate_json],
+    }
+appbuilder.add_view_no_menu(DruidPostAggregatorInlineView)
+
+
 class DatabaseView(CaravelModelView, DeleteMixin):  # noqa
     datamodel = SQLAInterface(models.Database)
     list_columns = ['database_name', 'sql_link', 'creator', 'changed_on']
@@ -394,7 +407,9 @@ class DruidDatasourceModelView(CaravelModelView, DeleteMixin):  # noqa
         'creator', 'created_on',
         'changed_by_', 'changed_on',
         'offset']
-    related_views = [DruidColumnInlineView, DruidMetricInlineView]
+    related_views = [
+        DruidColumnInlineView, DruidMetricInlineView,
+        DruidPostAggregatorInlineView]
     edit_columns = [
         'datasource_name', 'cluster', 'description', 'owner',
         'is_featured', 'is_hidden', 'default_endpoint', 'offset',