diff --git a/cyborg/db/sqlalchemy/alembic/versions/ede4e3f1a232_new_db_schema.py b/cyborg/db/sqlalchemy/alembic/versions/ede4e3f1a232_new_db_schema.py
index 34260072..2a7b1b6f 100644
--- a/cyborg/db/sqlalchemy/alembic/versions/ede4e3f1a232_new_db_schema.py
+++ b/cyborg/db/sqlalchemy/alembic/versions/ede4e3f1a232_new_db_schema.py
@@ -143,7 +143,9 @@ def upgrade():
         sa.Column('updated_at', sa.DateTime(), nullable=True),
         sa.Column('id', sa.Integer(), nullable=False),
         sa.Column('uuid', sa.String(length=36), nullable=False, unique=True),
-        sa.Column('project_id', sa.String(length=255), nullable=False),
+        # NOTICE: we don't have project related constraints in Stein Release,
+        # set nullable=True but keep this field for further expansion.
+        sa.Column('project_id', sa.String(length=255), nullable=True),
         sa.Column('state', state, nullable=False, default='Initial'),
         sa.Column('device_profile_id', sa.Integer(),
                   sa.ForeignKey('device_profiles.id', ondelete="RESTRICT"),
diff --git a/cyborg/db/sqlalchemy/models.py b/cyborg/db/sqlalchemy/models.py
index 557551f1..db6a5ae9 100644
--- a/cyborg/db/sqlalchemy/models.py
+++ b/cyborg/db/sqlalchemy/models.py
@@ -171,8 +171,9 @@ class DeviceProfile(Base):
     profile_json = Column(Text, nullable=False)
 
 
-class ExtendedAcceleratorRequest(Base):
-    """Represents extended nova requests for attach related operations."""
+class ExtArq(Base):
+    """ExtArq is the abbreviation of ExtendedAcceleratorRequest, it represents
+    extended nova requests for attach related operations."""
 
     __tablename__ = 'extended_accelerator_requests'
     __table_args__ = (
@@ -187,7 +188,7 @@ class ExtendedAcceleratorRequest(Base):
 
     id = Column(Integer, primary_key=True)
     uuid = Column(String(36), nullable=False, unique=True)
-    project_id = Column(String(255), nullable=False)
+    project_id = Column(String(255), nullable=True)
     state = Column(Enum('Initial', 'Bound', 'BindFailed', name='state'),
                    nullable=False)
     device_profile_id = Column(Integer, ForeignKey('device_profiles.id',