Add migration of sqlalchemy user column to tags (mlflow#1360)

mlflow/alembic/versions/90e64c465722_migrate_user_column_to_tags.py

@@ -0,0 +1,68 @@
+"""migrate user column to tags
+
+Revision ID: 90e64c465722
+Revises: 451aebb31d03
+Create Date: 2019-05-29 10:43:52.919427
+
+"""
+from alembic import op
+import sqlalchemy as sa
+from sqlalchemy import orm, Column, Integer, String, ForeignKey, PrimaryKeyConstraint
+from sqlalchemy.ext.declarative import declarative_base
+from sqlalchemy.orm import relationship, backref
+from mlflow.utils.mlflow_tags import MLFLOW_USER
+
+# revision identifiers, used by Alembic.
+revision = '90e64c465722'
+down_revision = '451aebb31d03'
+branch_labels = None
+depends_on = None
+
+
+Base = declarative_base()
+
+
+class SqlRun(Base):
+    __tablename__ = 'runs'
+    run_uuid = Column(String(32), nullable=False)
+    user_id = Column(String(256), nullable=True, default=None)
+    experiment_id = Column(Integer)
+
+    __table_args__ = (
+        PrimaryKeyConstraint('experiment_id', name='experiment_pk'),
+    )
+
+
+class SqlTag(Base):
+    __tablename__ = 'tags'
+    key = Column(String(250))
+    value = Column(String(250), nullable=True)
+    run_uuid = Column(String(32), ForeignKey('runs.run_uuid'))
+    run = relationship('SqlRun', backref=backref('tags', cascade='all'))
+
+    __table_args__ = (
+        PrimaryKeyConstraint('key', 'run_uuid', name='tag_pk'),
+    )
+
+
+def upgrade():
+    bind = op.get_bind()
+    session = orm.Session(bind=bind)
+    runs = session.query(SqlRun).all()
+    for run in runs:
+        if not run.user_id:
+            continue
+
+        tag_exists = False
+        for tag in run.tags:
+            if tag.key == MLFLOW_USER:
+                tag_exists = True
+        if tag_exists:
+            continue
+
+        session.merge(SqlTag(run_uuid=run.run_uuid, key=MLFLOW_USER, value=run.user_id))
+    session.commit()
+
+
+def downgrade():
+    pass