mastodon/db/migrate/20170713112503_make_tag_search_case_insensitive.rb

class MakeTagSearchCaseInsensitive < ActiveRecord::Migration[5.1]
  def up
    remove_index :tags, name: :hashtag_search_index
    execute 'CREATE INDEX hashtag_search_index ON tags (lower(name) text_pattern_ops);'
  end

  def down
    remove_index :tags, name: :hashtag_search_index
    execute 'CREATE INDEX hashtag_search_index ON tags (name text_pattern_ops);'
  end
end