Basic integration with ClickHouse

docs/installation.rst

@@ -211,6 +211,9 @@ Here's a list of some of the recommended packages.
 |  Vertica      | ``pip install                       |  ``vertica+vertica_python://``                  |
 |               | sqlalchemy-vertica-python``         |                                                 |
 +---------------+-------------------------------------+-------------------------------------------------+
+|  ClickHouse   | ``pip install                       | ``clickhouse://``                               |
+|               | sqlalchemy-clickhouse``             |                                                 |
++---------------+-------------------------------------+-------------------------------------------------+
 
 Note that many other database are supported, the main criteria being the
 existence of a functional SqlAlchemy dialect and Python driver. Googling

superset/connectors/sqla/models.py

@@ -370,6 +370,9 @@ def get_sqla_query(  # sqla
         if granularity not in self.dttm_cols:
             granularity = self.main_dttm_col
 
+        # Database spec supports join-free timeslot grouping
+        time_groupby_inline = self.database.db_engine_spec.time_groupby_inline
+
         cols = {col.column_name: col for col in self.columns}
         metrics_dict = {m.metric_name: m for m in self.metrics}
 
@@ -386,7 +389,7 @@ def get_sqla_query(  # sqla
         if timeseries_limit_metric:
             timeseries_limit_metric_expr = \
                 timeseries_limit_metric.sqla_col
-        if metrics:
+        if metrics_exprs:
             main_metric_expr = metrics_exprs[0]
         else:
             main_metric_expr = literal_column("COUNT(*)").label("ccount")
@@ -436,13 +439,20 @@ def visit_column(element, compiler, **kw):
 
             dttm_col = cols[granularity]
             time_grain = extras.get('time_grain_sqla')
+            time_filters = []
 
             if is_timeseries:
                 timestamp = dttm_col.get_timestamp_expression(time_grain)
                 select_exprs += [timestamp]
                 groupby_exprs += [timestamp]
 
-            time_filter = dttm_col.get_time_filter(from_dttm, to_dttm)
+            # Use main dttm column to support index with secondary dttm columns
+            if self.database.db_engine_spec.time_secondary_columns and \
+                    self.main_dttm_col in self.dttm_cols and \
+                    self.main_dttm_col != dttm_col.column_name:
+                time_filters.append(cols[self.main_dttm_col].
+                                    get_time_filter(from_dttm, to_dttm))
+            time_filters.append(dttm_col.get_time_filter(from_dttm, to_dttm))
 
         select_exprs += metrics_exprs
         qry = sa.select(select_exprs)
@@ -509,7 +519,7 @@ def visit_column(element, compiler, **kw):
                 having = template_processor.process_template(having)
                 having_clause_and += [sa.text('({})'.format(having))]
         if granularity:
-            qry = qry.where(and_(*([time_filter] + where_clause_and)))
+            qry = qry.where(and_(*(time_filters + where_clause_and)))
         else:
             qry = qry.where(and_(*where_clause_and))
         qry = qry.having(and_(*having_clause_and))
@@ -522,7 +532,8 @@ def visit_column(element, compiler, **kw):
 
         qry = qry.limit(row_limit)
 
-        if is_timeseries and timeseries_limit and groupby:
+        if is_timeseries and \
+                timeseries_limit and groupby and not time_groupby_inline:
             # some sql dialects require for order by expressions
             # to also be in the select clause -- others, e.g. vertica,
             # require a unique inner alias
@@ -620,8 +631,7 @@ def fetch_metadata(self):
             if not any_date_col and dbcol.is_time:
                 any_date_col = col.name
 
-            quoted = "{}".format(
-                column(dbcol.column_name).compile(dialect=db_dialect))
+            quoted = "{}".format(col.compile(dialect=db_dialect))
             if dbcol.sum:
                 metrics.append(M(
                     metric_name='sum__' + dbcol.column_name,

superset/db_engine_specs.py

@@ -50,7 +50,9 @@ class BaseEngineSpec(object):
     engine = 'base'  # str as defined in sqlalchemy.engine.engine
     cursor_execute_kwargs = {}
     time_grains = tuple()
+    time_groupby_inline = False
     limit_method = LimitMethod.FETCH_MANY
+    time_secondary_columns = False
 
     @classmethod
     def fetch_data(cls, cursor, limit):
@@ -865,6 +867,44 @@ def convert_dttm(cls, target_type, dttm):
     def epoch_to_dttm(cls):
         return "from_unixtime({col})"
 
+
+class ClickHouseEngineSpec(BaseEngineSpec):
+    """Dialect for ClickHouse analytical DB."""
+
+    engine = 'clickhouse'
+
+    time_secondary_columns = True
+    time_groupby_inline = True
+    time_grains = (
+        Grain('Time Column', _('Time Column'), '{col}'),
+        Grain('minute', _('minute'),
+              "toStartOfMinute(toDateTime({col}))"),
+        Grain('5 minute', _('5 minute'),
+              "toDateTime(intDiv(toUInt32(toDateTime({col})), 300)*300)"),
+        Grain('10 minute', _('10 minute'),
+              "toDateTime(intDiv(toUInt32(toDateTime({col})), 600)*600)"),
+        Grain('hour', _('hour'),
+              "toStartOfHour(toDateTime({col}))"),
+        Grain('day', _('day'),
+              "toStartOfDay(toDateTime({col}))"),
+        Grain('month', _('month'),
+              "toStartOfMonth(toDateTime({col}))"),
+        Grain('quarter', _('quarter'),
+              "toStartOfQuarter(toDateTime({col}))"),
+        Grain('year', _('year'),
+              "toStartOfYear(toDateTime({col}))"),
+    )
+
+    @classmethod
+    def convert_dttm(cls, target_type, dttm):
+        tt = target_type.upper()
+        if tt == 'DATE':
+            return "toDate('{}')".format(dttm.strftime('%Y-%m-%d'))
+        if tt == 'DATETIME':
+            return "toDateTime('{}')".format(
+                dttm.strftime('%Y-%m-%d %H:%M:%S'))
+        return "'{}'".format(dttm.strftime('%Y-%m-%d %H:%M:%S'))
+
 engines = {
     o.engine: o for o in globals().values()
     if inspect.isclass(o) and issubclass(o, BaseEngineSpec)}

superset/viz.py

@@ -130,7 +130,9 @@ def query_obj(self):
         # [column_name in list_of_values]. `__` prefix is there to avoid
         # potential conflicts with column that would be named `from` or `to`
         since = (
-            extra_filters.get('__from') or form_data.get("since", "1 year ago")
+            extra_filters.get('__from') or
+            form_data.get("since") or
+            config.get("SUPERSET_DEFAULT_SINCE", "1 year ago")
         )
 
         from_dttm = utils.parse_human_datetime(since)