Sequel.migration do
  change do
    alter_table(:log_parts) do
      add_index :created_at, concurrently: true
    end
  end
end

Sequel.migration do
  no_transaction

  change do
    alter_table(:log_parts) do
      add_index :created_at, concurrently: true
    end
  end
end

Disable transaction in log_parts(created_at) index migration
Disable transaction in log_parts(created_at) index migration

CREATE INDEX CONCURRENTLY does not support being run in a transaction.
