Collection.select(:portable_data_hash, :manifest_text).where(portable_data_hash: pdhs).distinct(:portable_data_hash).each do |c|
ActiveRecord::Base.connection.exec_query("update collections set file_names=$1 where portable_data_hash=$2",
"update file_names index",
Collection.select(:portable_data_hash, :manifest_text).where(portable_data_hash: pdhs).distinct(:portable_data_hash).each do |c|
ActiveRecord::Base.connection.exec_query("update collections set file_names=$1 where portable_data_hash=$2",
"update file_names index",