new_contents: """Create request search column and trigger.
  
  Revision ID: 5563ca9e7626
  Revises: 30d3af507801
  Create Date: 2014-03-06 13:13:52.831868
  
  """
  
  # revision identifiers, used by Alembic.
  revision = '5563ca9e7626'
  down_revision = '30d3af507801'
  
  from alembic import op
  import sqlalchemy as sa
  
  def upgrade():
      # TODO(cj@postcode.io): This should probably be rewritten using Alembic and SQLAlchemy classes,
      # but I couldn't find the docs on using `to_tsvector` in this context. Le sigh.
      op.execute("CREATE INDEX request_search_index ON request USING gin(to_tsvector('english', text))")
  
  def downgrade():
      op.drop_index("request_search_index", "request")
  
subject: Create a searchable index on the request text field.