[schema] Updating the base metric schema

UPDATING.md

@@ -32,6 +32,11 @@ which adds missing non-nullable fields and uniqueness constraints to the
 `columns`and `table_columns` tables. Depending on the integrity of the data,
 manual intervention may be required.
 
+* [5453](https://github.com/apache/incubator-superset/pull/5453): a change
+which adds missing non-nullable fields and uniqueness constraints to the metrics
+and sql_metrics tables. Depending on the integrity of the data, manual
+intervention may be required.
+
 ## Superset 0.32.0
 
 * `npm run backend-sync` is deprecated and no longer needed, will fail if called

superset/connectors/base/models.py

@@ -411,7 +411,7 @@ class BaseMetric(AuditMixinNullable, ImportMixin):
     __tablename__ = None  # {connector_name}_metric
 
     id = Column(Integer, primary_key=True)
-    metric_name = Column(String(512))
+    metric_name = Column(String(255), nullable=False)
     verbose_name = Column(String(1024))
     metric_type = Column(String(32))
     description = Column(Text)

superset/connectors/druid/models.py

@@ -341,15 +341,14 @@ class DruidMetric(Model, BaseMetric):
 
     __tablename__ = 'metrics'
     __table_args__ = (UniqueConstraint('metric_name', 'datasource_id'),)
-    datasource_id = Column(
-        Integer,
-        ForeignKey('datasources.id'))
+    datasource_id = Column(Integer, ForeignKey('datasources.id'))
+
     # Setting enable_typechecks=False disables polymorphic inheritance.
     datasource = relationship(
         'DruidDatasource',
         backref=backref('metrics', cascade='all, delete-orphan'),
         enable_typechecks=False)
-    json = Column(Text)
+    json = Column(Text, nullable=False)
 
     export_fields = (
         'metric_name', 'verbose_name', 'metric_type', 'datasource_id',

superset/connectors/sqla/models.py

@@ -209,7 +209,7 @@ class SqlMetric(Model, BaseMetric):
         'SqlaTable',
         backref=backref('metrics', cascade='all, delete-orphan'),
         foreign_keys=[table_id])
-    expression = Column(Text)
+    expression = Column(Text, nullable=False)
 
     export_fields = (
         'metric_name', 'verbose_name', 'metric_type', 'table_id', 'expression',

superset/migrations/versions/e9df189e5c7e_update_base_metrics.py

@@ -0,0 +1,169 @@
+# Licensed to the Apache Software Foundation (ASF) under one
+# or more contributor license agreements.  See the NOTICE file
+# distributed with this work for additional information
+# regarding copyright ownership.  The ASF licenses this file
+# to you under the Apache License, Version 2.0 (the
+# "License"); you may not use this file except in compliance
+# with the License.  You may obtain a copy of the License at
+#
+#   http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing,
+# software distributed under the License is distributed on an
+# "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+# KIND, either express or implied.  See the License for the
+# specific language governing permissions and limitations
+# under the License.
+"""update base metrics
+
+Note that the metrics table was previously partially modifed by revision
+f231d82b9b26.
+
+Revision ID: e9df189e5c7e
+Revises: 7f2635b51f5d
+Create Date: 2018-07-20 15:57:48.118304
+
+"""
+
+# revision identifiers, used by Alembic.
+revision = 'e9df189e5c7e'
+down_revision = '7f2635b51f5d'
+
+from alembic import op
+from sqlalchemy import Column, engine, Integer, String, Text
+from sqlalchemy.ext.declarative import declarative_base
+
+from superset import db
+from superset.utils.core import generic_find_uq_constraint_name
+
+Base = declarative_base()
+
+conv = {
+    'uq': 'uq_%(table_name)s_%(column_0_name)s',
+}
+
+
+class BaseMetricMixin:
+    id = Column(Integer, primary_key=True)
+
+
+class DruidMetric(BaseMetricMixin, Base):
+    __tablename__ = 'metrics'
+
+    datasource_id = Column(Integer)
+
+
+class SqlMetric(BaseMetricMixin, Base):
+    __tablename__ = 'sql_metrics'
+
+    table_id = Column(Integer)
+
+
+def upgrade():
+    bind = op.get_bind()
+    session = db.Session(bind=bind)
+
+    # Delete the orphaned metrics records.
+    for record in session.query(DruidMetric).all():
+        if record.datasource_id is None:
+            session.delete(record)
+
+    session.commit()
+
+    # Enforce that metrics.metric_name column be non-nullable.
+    with op.batch_alter_table('metrics') as batch_op:
+        batch_op.alter_column(
+            'metric_name',
+            existing_type=String(255),
+            nullable=False,
+        )
+
+    # Enforce that metrics.json column be non-nullable.
+    with op.batch_alter_table('metrics') as batch_op:
+        batch_op.alter_column(
+            'json',
+            existing_type=Text,
+            nullable=False,
+        )
+
+    # Delete the orphaned sql_metrics records.
+    for record in session.query(SqlMetric).all():
+        if record.table_id is None:
+            session.delete(record)
+
+    session.commit()
+
+    # Reduce the size of the sql_metrics.metric_name column for constraint
+    # viability and enforce that it to be non-nullable.
+    with op.batch_alter_table('sql_metrics') as batch_op:
+        batch_op.alter_column(
+            'metric_name',
+            existing_type=String(512),
+            nullable=False,
+            type_=String(255),
+        )
+
+    # Enforce that sql_metrics.expression column be non-nullable.
+    with op.batch_alter_table('sql_metrics') as batch_op:
+        batch_op.alter_column(
+            'expression',
+            existing_type=Text,
+            nullable=False,
+        )
+
+    # Add the missing uniqueness constraint to the sql_metrics table.
+    with op.batch_alter_table('sql_metrics', naming_convention=conv) as batch_op:
+        batch_op.create_unique_constraint(
+            'uq_sql_metrics_metric_name',
+            ['metric_name', 'table_id'],
+        )
+
+
+def downgrade():
+    bind = op.get_bind()
+    insp = engine.reflection.Inspector.from_engine(bind)
+
+    # Remove the missing uniqueness constraint from the sql_metrics table.
+    with op.batch_alter_table('sql_metrics', naming_convention=conv) as batch_op:
+        batch_op.drop_constraint(
+            generic_find_uq_constraint_name(
+                'sql_metrics',
+                {'metric_name', 'table_id'},
+                insp,
+            ) or 'uq_sql_metrics_table_id',
+            type_='unique',
+        )
+
+    # Restore the size of the sql_metrics.metric_name column and forego that it
+    # be non-nullable.
+    with op.batch_alter_table('sql_metrics') as batch_op:
+        batch_op.alter_column(
+            'metric_name',
+            existing_type=String(255),
+            nullable=True,
+            type_=String(512),
+        )
+
+    # Forego that the sql_metrics.expression column be non-nullable.
+    with op.batch_alter_table('sql_metrics') as batch_op:
+        batch_op.alter_column(
+            'expression',
+            existing_type=Text,
+            nullable=True,
+        )
+
+    # Forego that the metrics.metric_name column be non-nullable.
+    with op.batch_alter_table('metrics') as batch_op:
+        batch_op.alter_column(
+            'metric_name',
+            existing_type=String(255),
+            nullable=True,
+        )
+
+    # Forego that the metrics.json column be non-nullable.
+    with op.batch_alter_table('metrics') as batch_op:
+        batch_op.alter_column(
+            'json',
+            existing_type=Text,
+            nullable=True,
+        )

tests/dict_import_export_tests.py

@@ -72,7 +72,7 @@ def create_table(
             'params': json.dumps(params),
             'columns': [{'column_name': c}
                         for c in cols_names],
-            'metrics': [{'metric_name': c} for c in metric_names],
+            'metrics': [{'metric_name': c, 'expression': ''} for c in metric_names],
         }
 
         table = SqlaTable(
@@ -84,7 +84,7 @@ def create_table(
         for col_name in cols_names:
             table.columns.append(TableColumn(column_name=col_name))
         for metric_name in metric_names:
-            table.metrics.append(SqlMetric(metric_name=metric_name))
+            table.metrics.append(SqlMetric(metric_name=metric_name, expression=''))
         return table, dict_rep
 
     def create_druid_datasource(
@@ -98,7 +98,7 @@ def create_druid_datasource(
             'id': id,
             'params': json.dumps(params),
             'columns': [{'column_name': c} for c in cols_names],
-            'metrics': [{'metric_name': c} for c in metric_names],
+            'metrics': [{'metric_name': c, 'json': '{}'} for c in metric_names],
         }
 
         datasource = DruidDatasource(

tests/import_export_tests.py

@@ -113,7 +113,7 @@ def create_table(
             table.columns.append(
                 TableColumn(column_name=col_name))
         for metric_name in metric_names:
-            table.metrics.append(SqlMetric(metric_name=metric_name))
+            table.metrics.append(SqlMetric(metric_name=metric_name, expression=''))
         return table
 
     def create_druid_datasource(
@@ -130,7 +130,7 @@ def create_druid_datasource(
                 DruidColumn(column_name=col_name))
         for metric_name in metric_names:
             datasource.metrics.append(DruidMetric(
-                metric_name=metric_name))
+                metric_name=metric_name, json='{}'))
         return datasource
 
     def get_slice(self, slc_id):