Delete username unique index from User table

CLOUDBLD-7737

Cachito DB currently uses 'username' in table User as both unique constraint
and unique index. Alembic will attempt to drop the unique constraint as they
are redundant. To prevent this, drop ix_user_username - the unique index.

Signed-off-by: Daniel Cho <dacho@redhat.com>

cachito/web/migrations/versions/02229e089b24_delete_user_username_index.py

@@ -0,0 +1,26 @@
+"""Remove User.username unique index
+
+Revision ID: 02229e089b24
+Revises: 7d979987402d
+Create Date: 2021-12-15 21:37:30.582812
+
+"""
+from alembic import op
+import sqlalchemy as sa
+
+
+# revision identifiers, used by Alembic.
+revision = "02229e089b24"
+down_revision = "7d979987402d"
+branch_labels = None
+depends_on = None
+
+
+def upgrade():
+    with op.batch_alter_table("user", schema=None) as batch_op:
+        batch_op.drop_index("ix_user_username")
+
+
+def downgrade():
+    with op.batch_alter_table("user", schema=None) as batch_op:
+        batch_op.create_index("ix_user_username", ["username"], unique=True)

cachito/web/models.py

@@ -764,7 +764,7 @@ class User(db.Model, UserMixin):
     """Represents an external user that owns a Cachito request."""
 
     id = db.Column(db.Integer, primary_key=True)
-    username = db.Column(db.String, index=True, unique=True, nullable=False)
+    username = db.Column(db.String, unique=True, nullable=False)
     requests = db.relationship("Request", foreign_keys=[Request.user_id], back_populates="user")
 
     @classmethod