chaos_order_1.sql

-- DO NOT RUN IN PRODUCTION
-- Supported on PSQL 9.6+.
-- Note: If all your tables aren’t located in the public schema
--           be sure to modify the specified schemaname
do $$
declare
    selectrow record;
begin
for selectrow in
    select 
      '
        ALTER TABLE '|| T.mytable || ' ADD COLUMN IF NOT EXISTS  _rand decimal DEFAULT random();
        CREATE INDEX IF NOT EXISTS _rand_index_'|| T.mytable || ' on  '|| T.mytable || '(_rand);
        CLUSTER '|| T.mytable || ' USING _rand_index_'|| T.mytable || ';
      ' as script 

   from 
      ( 
        select tablename as mytable from pg_tables where schemaname  ='public' --your schema name here
      ) t
loop
execute selectrow.script;
end loop;
end;
$$;