pleroma/priv/repo/migrations/20170917120416_add_tag_index.exs

defmodule Pleroma.Repo.Migrations.AddTagIndex do
  use Ecto.Migration

  @disable_ddl_transaction true

  def change do
    create index(:activities, ["(data #> '{\"object\",\"tag\"}')"], concurrently: true, using: :gin, name: :activities_tags)
  end
end