dynamic_upsert_for_updating_tables.sql

CREATE OR REPLACE FUNCTION update_table (target_table text, timestamp_col text,
  from_timestamp timestamp with time zone, constraint_name text, t ANYELEMENT)
    RETURNS SETOF ANYELEMENT
AS $$
DECLARE
    querytext text;
DECLARE
    tmp text;
BEGIN
    SELECT
        string_agg('"' || column_name || '"' || ' = EXCLUDED."' || column_name || '"', ',')
    FROM
        information_schema.columns
    WHERE
        table_name = target_table AND table_schema = 'public' 
    INTO 
       tmp;
    querytext = format(
      'INSERT INTO public.%s '
      'SELECT * from production.%s WHERE %s > ''%s'' '
      'ON CONFLICT ON CONSTRAINT %s DO UPDATE SET %s RETURNING *',
      target_table, target_table, timestamp_col, from_timestamp, constraint_name, tmp);
    raise log 'executing dynamic query %s', querytext;
    RETURN QUERY EXECUTE querytext;
END
$$
LANGUAGE plpgsql;