old_contents: """migrate event descriptions
  
  Revision ID: ea9dc8742ee
  Revises: 56500282e024
  Create Date: 2015-06-23 18:09:33.804125
  
  """
  
  # revision identifiers, used by Alembic.
  revision = 'ea9dc8742ee'
  down_revision = '56500282e024'
  
  from alembic import op
  
  
  def upgrade():
      conn = op.get_bind()
      while True:
          res = conn.execute(
              'UPDATE event SET _description=description '
              'WHERE _description IS NULL LIMIT 100000')
          print 'Updated {} rows'.format(res.rowcount)
          if res.rowcount == 0:
              return
  
  
  def downgrade():
      pass
  
new_contents: """migrate event descriptions
  
  Revision ID: ea9dc8742ee
  Revises: 56500282e024
  Create Date: 2015-06-23 18:09:33.804125
  
  """
  
  # revision identifiers, used by Alembic.
  revision = 'ea9dc8742ee'
  down_revision = '56500282e024'
  
  from alembic import op
  
  
  def upgrade():
      conn = op.get_bind()
      while True:
          res = conn.execute(
              'UPDATE event SET _description=description '
              'WHERE _description IS NULL AND _description!=description LIMIT 100000')
          print 'Updated {} rows'.format(res.rowcount)
          if res.rowcount == 0:
              return
  
  
  def downgrade():
      pass
  
subject: Fix migration.